EP4306669A1

EP4306669A1 - Aluminum alloy extruded material and electronic device housing comprising same

Info

Publication number: EP4306669A1
Application number: EP22853334.5A
Authority: EP
Inventors: Jinhwan Jeong; Jungwoo Choi; Sungho Cho; Seungchang BAEK; Yoonhee LEE; Byounguk Yoon
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2021-08-02
Filing date: 2022-07-27
Publication date: 2024-01-17
Also published as: US20230407440A1; WO2023013956A1

Abstract

An aluminum alloy extruded material and an electronic device housing including the same are disclosed. According to various embodiments, the aluminum alloy extruded material includes aluminum, zinc, magnesium, and copper, and the amount of copper and the amount of zinc may have a correlation. Various other embodiments are also possible.

Description

Technical Field

Various embodiments of the present disclosure relate to an aluminum alloy extruded material and an electronic device housing including the same.

Background Art

An electronic device may be a device that performs a specific function according to a loaded program, such as a home appliance, an electronic note, a portable multimedia player, a mobile communication terminal, a tablet personal computer (PC), a video/audio device, a desktop/laptop computer, a vehicle navigation system, and the like. For example, such electronic devices may output stored information as sound or images. Along with an increase in the integration level of electronic devices and the increasing popularity of ultra-high-speed, large-capacity wireless communication, various functions have recently been loaded into a single electronic device, such as a mobile communication terminal. For example, an entertainment function such as gaming, a multimedia function such as music/video play, a communication and security function for mobile banking, a scheduling function, and an electronic wallet function, as well as a communication function, have been integrated into a single electronic device.
An electronic device includes a housing that may be formed of various materials, and the housing of the electronic device protects internal components of the electronic device from an external impact. In addition, the housing of the electronic device may be manufactured such that the electronic device is easy for a user to carry and made to be aesthetically pleasing to the user. The housing of the electronic device may need to have high strength and hardness to protect various internal components and modules of the electronic device, and may be excellent in gloss for the exterior quality.
As an electronic device housing, an alloy for aluminum extrusion may be used. An aluminum alloy may be excellent in rigidity and have a high gloss and/or glossy surface characteristic of a metal. However, since the rigidity and exterior quality conflict with each other, an aluminum alloy with high rigidity has low exterior quality and an aluminum alloy with improved exterior quality has low rigidity. Thus, it may be difficult to use the above aluminum alloys in an electronic device.

Disclosure of the Invention

Technical Solutions

Various embodiments provide an alloy extruded material including aluminum and various metal elements as an aluminum alloy extruded material.
Various embodiments provide an aluminum alloy extruded material that is excellent in strength and hardness and adhesion of a surface oxide film while realizing a high gloss and/or glossy surface characteristic.
The aluminum alloy extruded material according to various embodiments may include aluminum, zinc, magnesium, and copper, and an amount of copper and an amount of zinc may correlate.
An electronic device housing according to various embodiments may include an aluminum alloy extruded material or may be surrounded and formed by the aluminum alloy extruded material.
A method of preparing an aluminum alloy extruded material according to various embodiments may include a step of preparing an aluminum metal, a step of forming an aluminum alloy by melting the aluminum metal and adding metal elements including zinc and magnesium, a step of heating and extruding the aluminum alloy, and a step of performing a heat treatment on the extruded aluminum alloy to form an aluminum alloy extruded material.

Effects

According to various embodiments, an alloy extruded material including aluminum and various metal elements may be provided as an aluminum alloy extruded material.
According to various embodiments, an aluminum alloy extruded material excellent in strength and hardness and adhesion of a surface oxide film while realizing a high gloss and/or glossy surface characteristic may be provided.

Brief Description of Drawings

FIG. 1 is a block diagram illustrating an electronic device in a network environment according to various embodiments.
FIG. 2 is a flowchart of steps of a method of preparing an aluminum alloy extruded material according to various embodiments.
FIG. 3 is a flowchart of a method of preparing an aluminum alloy extruded material according to various embodiments.
FIG. 4 is an image obtained by capturing a cross section of an aluminum alloy extruded material according to an embodiment.

Best Mode for Carrying Out the Invention

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. When describing the embodiments with reference to the accompanying drawings, like reference numerals refer to like components and a repeated description related thereto will be omitted.
FIG. 1 is a block diagram illustrating an electronic device 101 in a network environment 100 according to various embodiments.
Referring to FIG. 1, the electronic device 101 in the network environment 100 may communicate with an electronic device 102 via a first network 198 (e.g., a short-range wireless communication network), or communicate with at least one of an electronic device 104 or a server 108 via a second network 199 (e.g., a long-range wireless communication network). According to an embodiment, the electronic device 101 may communicate with the electronic device 104 via the server 108. According to an embodiment, the electronic device 101 may include a processor 120, a memory 130, an input module 150, a sound output module 155, a display module 160, an audio module 170, a sensor module 176, an interface 177, a connecting terminal 178, a haptic module 179, a camera module 180, a power management module 188, a battery 189, a communication module 190, a subscriber identification module (SIM) 196, or an antenna module 197. In some embodiments, at least one (e.g., the connecting terminal 178) of the above components may be omitted from the electronic device 101, or one or more other components may be added to the electronic device 101. In some embodiments, some (e.g., the sensor module 176, the camera module 180, or the antenna module 197) of the components may be integrated as a single component (e.g., the display module 160).
The processor 120 may execute, for example, software (e.g., a program 140) to control at least one other component (e.g., a hardware or software component) of the electronic device 101 connected to the processor 120, and may perform various data processing or computation. According to an embodiment, as at least a part of data processing or computation, the processor 120 may store a command or data received from another component (e.g., the sensor module 176 or the communication module 190) in a volatile memory 132, process the command or the data stored in the volatile memory 132, and store resulting data in a non-volatile memory 134. According to an embodiment, the processor 120 may include a main processor 121 (e.g., a central processing unit (CPU) or an application processor (AP)), or an auxiliary processor 123 (e.g., a graphics processing unit (GPU), a neural processing unit (NPU), an image signal processor (ISP), a sensor hub processor, or a communication processor (CP)) that is operable independently from, or in conjunction with the main processor 121. For example, when the electronic device 101 includes the main processor 121 and the auxiliary processor 123, the auxiliary processor 123 may be adapted to consume less power than the main processor 121 or to be specific to a specified function. The auxiliary processor 123 may be implemented as separate from, or as part of the main processor 121.
The auxiliary processor 123 may control at least some of functions or states related to at least one (e.g., the display module 160, the sensor module 176, or the communication module 190) of the components of the electronic device 101, instead of the main processor 121 while the main processor 121 is in an inactive (e.g., sleep) state, or together with the main processor 121 while the main processor 121 is in an active state (e.g., executing an application). According to an embodiment, the auxiliary processor 123 (e.g., an ISP or a CP) may be implemented as a portion of another component (e.g., the camera module 180 or the communication module 190) that is functionally related to the auxiliary processor 123. According to an embodiment, the auxiliary processor 123 (e.g., an NPU) may include a hardware structure specified for artificial intelligence model processing. An artificial intelligence model may be generated by machine learning. Such learning may be performed, for example, by the electronic device 101 in which an artificial intelligence model is executed, or via a separate server (e.g., the server 108). Learning algorithms may include, but are not limited to, for example, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning. The artificial intelligence model may include a plurality of artificial neural network layers. An artificial neural network may include, for example, a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), a deep Q-network, or a combination of two or more thereof, but is not limited thereto. The artificial intelligence model may additionally or alternatively include a software structure other than the hardware structure. The memory 130 may store various pieces of data used by at least one component (e.g., the processor 120 or the sensor module 176) of the electronic device 101. The various pieces of data may include, for example, software (e.g., the program 140) and input data or output data for a command related thereto. The memory 130 may include the volatile memory 132 or the non-volatile memory 134.
The program 140 may be stored as software in the memory 130 and may include, for example, an operating system (OS) 142, middleware 144, or an application 146.
The input module 150 may receive a command or data to be used by another component (e.g., the processor 120) of the electronic device 101, from the outside (e.g., a user) of the electronic device 101. The input module 150 may include, for example, a microphone, a mouse, a keyboard, a key (e.g., a button), or a digital pen (e.g., a stylus pen).
The sound output module 155 may output a sound signal to the outside of the electronic device 101. The sound output module 155 may include, for example, a speaker or a receiver. The speaker may be used for general purposes, such as playing multimedia or playing record. The receiver may be used to receive an incoming call. According to an embodiment, the receiver may be implemented as separate from, or as part of the speaker.
The display module 160 may visually provide information to the outside (e.g., a user) of the electronic device 101. The display module 160 may include, for example, a display, a hologram device, or a projector and control circuitry to control a corresponding one of the display, hologram device, and projector. According to an embodiment, the display module 160 may include a touch sensor adapted to sense a touch, or a pressure sensor adapted to measure the intensity of force incurred by the touch.
The audio module 170 may convert a sound into an electrical signal or vice versa.
According to an embodiment, the audio module 170 may obtain the sound via the input module 150 or output the sound via the sound output module 155 or an external electronic device (e.g., the electronic device 102 such as a speaker or headphones) directly or wirelessly connected to the electronic device 101.
The sensor module 176 may detect an operational state (e.g., power or temperature) of the electronic device 101 or an environmental state (e.g., a state of a user) external to the electronic device 101, and generate an electrical signal or data value corresponding to the detected state. According to an embodiment, the sensor module 176 may include, for example, a gesture sensor, a gyro sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor. The interface 177 may support one or more specified protocols to be used for the electronic device 101 to be coupled with the external electronic device (e.g., the electronic device 102) directly (e.g., by wire) or wirelessly. According to an embodiment, the interface 177 may include, for example, a high-definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface.
The connecting terminal 178 may include a connector via which the electronic device 101 may be physically connected to the external electronic device (e.g., the electronic device 102). According to an embodiment, the connecting terminal 178 may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector).
The haptic module 179 may convert an electrical signal into a mechanical stimulus (e.g., a vibration or a movement) or an electrical stimulus which may be recognized by a user via his or her tactile sensation or kinesthetic sensation. According to an embodiment, the haptic module 179 may include, for example, a motor, a piezoelectric element, or an electric stimulator.
The camera module 180 may capture a still image and moving images. According to an embodiment, the camera module 180 may include one or more lenses, image sensors, ISPs, or flashes.
The power management module 188 may manage power supplied to the electronic device 101. According to an embodiment, the power management module 188 may be implemented as at least part of, for example, a power management integrated circuit (PMIC). The battery 189 may supply power to at least one component of the electronic device 101. According to an embodiment, the battery 189 may include, for example, a primary cell which is not rechargeable, a secondary cell which is rechargeable, or a fuel cell.
The communication module 190 may support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device 101 and the external electronic device (e.g., the electronic device 102, the electronic device 104, or the server 108) and performing communication via the established communication channel. The communication module 190 may include one or more CPs that are operable independently of the processor 120 (e.g., an AP) and that support a direct (e.g., wired) communication or a wireless communication. According to an embodiment, the communication module 190 may include a wireless communication module 192 (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module 194 (e.g., a local area network (LAN) communication module, or a power line communication (PLC) module). A corresponding one of these communication modules may communicate with the external electronic device 104 via the first network 198 (e.g., a short-range communication network, such as Bluetooth^™, wireless-fidelity (Wi-Fi) direct, or infrared data association (IrDA)) or the second network 199 (e.g., a long-range communication network, such as a legacy cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., a LAN or a wide area network (WAN))). These various types of communication modules may be implemented as a single component (e.g., a single chip), or may be implemented as multiple components (e.g., multiple chips) separate from each other. The wireless communication module 192 may identify and authenticate the electronic device 101 in a communication network, such as the first network 198 or the second network 199, using subscriber information (e.g., international mobile subscriber identity (IMSI)) stored in the SIM 196.
The wireless communication module 192 may support a 5G network after a 4G network, and next-generation communication technology, e.g., new radio (NR) access technology. The NR access technology may support enhanced mobile broadband (eMBB), massive machine type communications (mMTC), or ultra-reliable and low-latency communications (URLLC). The wireless communication module 192 may support a high-frequency band (e.g., a mmWave band) to achieve, e.g., a high data transmission rate. The wireless communication module 192 may support various technologies for securing performance on a high-frequency band, such as, e.g., beamforming, massive multiple-input and multiple-output (massive MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beamforming, or a large scale antenna. The wireless communication module 192 may support various requirements specified in the electronic device 101, an external electronic device (e.g., the electronic device 104), or a network system (e.g., the second network 199). According to an embodiment, the wireless communication module 192 may support a peak data rate (e.g., 20 Gbps or more) for implementing eMBB, loss coverage (e.g., 164 dB or less) for implementing mMTC, or U-plane latency (e.g., 0.5 ms or less for each of downlink (DL) and uplink (UL), or a round trip of 1 ms or less) for implementing URLLC.
The antenna module 197 may transmit or receive a signal or power to or from the outside (e.g., an external electronic device) of the electronic device 101. According to an embodiment, the antenna module 197 may include an antenna including a radiating element including a conductive material or a conductive pattern formed in or on a substrate (e.g., a printed circuit board (PCB)). According to an embodiment, the antenna module 197 may include a plurality of antennas (e.g., array antennas). In such a case, at least one antenna appropriate for a communication scheme used in a communication network, such as the first network 198 or the second network 199, may be selected by, for example, the communication module 190 from the plurality of antennas. The signal or power may be transmitted or received between the communication module 190 and the external electronic device via the at least one selected antenna. According to an embodiment, another component (e.g., a radio frequency integrated circuit (RFIC)) other than the radiating element may be additionally formed as part of the antenna module 197.
According to various embodiments, the antenna module 197 may form a mmWave antenna module. According to an embodiment, the mmWave antenna module may include a PCB, an RFIC disposed on a first surface (e.g., the bottom surface) of the PCB or adjacent to the first surface and capable of supporting a designated high-frequency band (e.g., the mmWave band), and a plurality of antennas (e.g., array antennas) disposed on a second surface (e.g., the top or a side surface) of the PCB, or adjacent to the second surface and capable of transmitting or receiving signals in the designated high-frequency band.
At least some of the above-described components may be coupled mutually and communicate signals (e.g., commands or data) therebetween via an inter-peripheral communication scheme (e.g., a bus, general purpose input and output (GPIO), serial peripheral interface (SPI), or mobile industry processor interface (MIPI)).
According to an embodiment, commands or data may be transmitted or received between the electronic device 101 and the external electronic device 104 via the server 108 coupled with the second network 199. Each of the external electronic devices 102 and 104 may be a device of the same type as or a different type from the electronic device 101. According to an embodiment, all or some of operations to be executed at the electronic device 101 may be executed at one or more of external electronic devices (e.g., the external electronic devices 102 and 104, or the server 108). For example, if the electronic device 101 needs to perform a function or a service automatically, or in response to a request from a user or another device, the electronic device 101, instead of, or in addition to, executing the function or the service, may request the one or more external electronic devices to perform at least part of the function or the service. The one or more external electronic devices receiving the request may perform the at least part of the function or the service requested, or an additional function or an additional service related to the request, and transfer an outcome of the performing to the electronic device 101. The electronic device 101 may provide the outcome, with or without further processing of the outcome, as at least part of a reply to the request. To that end, a cloud computing, distributed computing, mobile edge computing (MEC), or client-server computing technology may be used, for example. The electronic device 101 may provide ultra low-latency services using, e.g., distributed computing or MEC. In another embodiment, the external electronic device 104 may include an Internet-of-things (IoT) device. The server 108 may be an intelligent server using machine learning and/or a neural network. According to an embodiment, the external electronic device 104 or the server 108 may be included in the second network 199. The electronic device 101 may be applied to intelligent services (e.g., a smart home, a smart city, a smart car, or healthcare) based on 5G communication technology or IoT-related technology.
An aluminum alloy extruded material according to various embodiments may include aluminum (Al); zinc (Zn); magnesium (Mg); and copper (Cu). According to various embodiments, an oxide film may be formed on a surface of the aluminum alloy extruded material. An anodizing (anodic oxidation) step may be performed on an aluminum alloy extruded material formed by adding zinc, magnesium, and copper to aluminum and melting and extruding the mixture. As the anodizing step is performed, an oxide film may be formed on a surface of the aluminum alloy extruded material.
According to various embodiments, the oxide film may be formed on the surface of the aluminum alloy extruded material, and a quality of an exterior of the aluminum alloy extruded material may be determined according to a characteristic of the oxide film. In addition, the oxide film formed on the surface of the aluminum alloy extruded material may not be easily detached.
According to various embodiments, an amount of copper and an amount of zinc may correlate. According to various embodiments, the amount of copper and the amount of zinc in the aluminum alloy extruded material may satisfy Equation 1 below. $[Cu] \geq 0.14 [Zn] - 0.782$
([Cu] corresponds to an amount (% by weight (wt%)) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn).)
According to various embodiments, the minimum amount of copper may be determined according to the amount of zinc in the aluminum alloy extruded material. According to various embodiments, since zinc is included in the aluminum alloy extruded material, the aluminum alloy extruded material may be excellent in rigidity, and detachment of an oxide film formed by performing the anodizing step may be prevented by adding copper together with zinc. According to various embodiments, when zinc is excessively included in the aluminum alloy extruded material beyond a predetermined range, the oxide film formed by performing the anodizing step may be easily detached, and accordingly, copper may desirably be added together in a predetermined range. According to various embodiments, to prevent the oxide film from being detached, the amount of copper may be set in proportion to the amount of zinc in the aluminum alloy extruded material. According to various embodiments, the amount of copper and the amount of zin in the aluminum alloy extruded material may satisfy Equation 1 described above. Based on the total weight of the aluminum alloy extruded material, zinc may be included in an amount of 5.85 wt% to 8.0 wt% and copper may be included in an amount of 0.03 wt% to 0.50 wt%.
According to various embodiments, a cutting step (e.g., computer numeric control (CNC) cutting) may be performed on the aluminum alloy extruded material to form an electronic device housing. When the cutting step is performed, corrosion resistance and/or machinability of the aluminum alloy extruded material may desirably be high, to form a desired shape and/or form. According to various embodiments, the aluminum alloy extruded material that contains aluminum, zinc, magnesium, and copper and that is formed by extrusion may be processed in the form of a housing suitable for an electronic device as the cutting step is performed. Since the aluminum alloy extruded material has a clean cut surface and is quickly cut due to excellent corrosion resistance and/or machinability, the aluminum alloy extruded material may be desirably used to manufacture, in particular, a small-sized part (e.g., a housing of a mobile electronic device).
According to various embodiments, the aluminum alloy extruded material may be cast through any manufacturing process performed according to standards. As a series of manufacturing steps known to one of ordinary skill in the aluminum industry, for example, a step of melting aluminum and then adding other metal elements, a step of casting a billet for extrusion, a homogenizing heat treatment step for a billet for extrusion, a step of performing extrusion during heating at a high temperature, an artificial aging heat treatment step for an aluminum alloy extruded through a heat treatment, a cutting step, and a surface oxidation treatment step (anodizing step) may be included, however, the manufacturing steps are not limited thereto. According to various embodiments, the artificial aging heat treatment step may increase rigidity of the extruded aluminum alloy.
According to various embodiments, the aluminum alloy extruded material may be excellent in extrudability. For example, a step of extruding an aluminum alloy may be performed by applying heat at a solidus temperature or less of the aluminum alloy, and an extrusion speed may be determined in consideration of a temperature rise due to frictional heat during extrusion. The aluminum alloy extruded material according to various embodiments may have a solidus temperature of 600°C or higher and may be heated at a preheating temperature of 500°C or higher, so that an extrusion load during extrusion and flow stress may be reduced.
According to various embodiments, the aluminum alloy extruded material may include metal elements including zinc, magnesium, and copper, and the remainder may contain aluminum. According to various embodiments, zinc (Zn) may be included in an amount of 5.85 wt% to 8.0 wt% based on the total weight of the aluminum alloy extruded material. Zinc may be bonded to magnesium in the aluminum alloy extruded material to form a Zn₂Mg strengthening phase. When the amount of zinc is less than 5.85 wt%, yield strength may decrease, and when the amount of zinc exceeds 8 wt%, corrosion resistance may decrease, and a plurality of segregations and a plurality of compounds containing zinc may be present in the aluminum alloy extruded material. For example, when the amount of zinc is less than 5.85 wt% based on the total weight of the aluminum alloy extruded material, the yield strength may be less than 450 megapascals (MPa), and when the amount of zinc exceeds 8 wt%, gloss of a surface of the oxide film formed by performing the anodizing step may be reduced to be less than 300 GU, and surface roughening may occur.
According to various embodiments, magnesium (Mg) may be included in an amount of 2 wt% to 2.9 wt% based on the total weight of the aluminum alloy extruded material. When the amount of magnesium is less than 2 wt% based on the total weight of the aluminum alloy extruded material, the yield strength may decrease, and when the amount of magnesium exceeds 2.9 wt%, extrudability may be reduced due to a low solidus temperature of the aluminum alloy extruded material. For example, when the amount of magnesium is less than 2 wt% based on the total weight of the aluminum alloy extruded material, the yield strength may be less than 450 MPa, and when the amount of magnesium exceeds 2.9 wt%, it may be difficult to apply a high extrusion temperature, and accordingly, the extrusion speed may decrease, a crack may occur, and gloss of the surface may be reduced to be less than 300 GU after the oxide film is formed through the anodizing step.
According to various embodiments, the amount of zinc and the amount of magnesium may satisfy Equation 2 below. $2 \leq \frac{[Zn]}{[Mg]} \leq 4$
([Zn] corresponds to the amount (wt%) of zinc (Zn), and [Mg] corresponds to the amount (wt%) of magnesium (Mg).)
According to various embodiments, a ratio of the amount of zinc to the amount of magnesium in the aluminum alloy extruded material may range from "2" to "4". When the ratio of the amount of zinc to the amount of magnesium is less than "2", the aluminum alloy extruded material may have high rigidity due to a relatively large amount of magnesium, however, at least one of the extrudability and/or extrusion speed may be reduced, and the surface gloss may be reduced after the anodizing step is performed. When the ratio of the amount of zinc to the amount of magnesium exceeds "4", the corrosion resistance of the aluminum alloy extruded material may be reduced due to a relatively large amount of zinc, the surface gloss may be reduced after the anodizing step is performed by at least one of a segregation and/or compound formed by an excessive amount of zinc, and surface roughening may occur. According to various embodiments, an intermetallic compound including Zn₂Mg may be formed by bonding zinc and magnesium in the aluminum alloy extruded material. The intermetallic compound may be formed by bonding between metal elements added to the aluminum alloy extruded material. A plurality of intermetallic compounds may be dispersed in the aluminum alloy extruded material, and when the size of the intermetallic compound decreases, a scratch may not be left on the oxide film on the surface that is etched as the anodizing step is performed. As the number of fine intermetallic compounds with a small diameter increases, the gloss may increase. According to various embodiments, the diameter of the intermetallic compound may be 10 micrometers (µm) or less. Desirably, the diameter of the intermetallic compound may be 6 µm or less. For example, the diameter of the intermetallic compound may refer to an average diameter of intermetallic compounds. According to various embodiments, the aluminum alloy extruded material may be formed of a plurality of grain structures. The aluminum alloy extruded material may be formed by extruding an aluminum alloy formed by casting dissolved aluminum, and crystal grains may be formed during a cooling process in which the aluminum alloy extruded material is gradually cooled. The size of a crystal grain of the aluminum alloy extruded material may be determined according to at least one of the type and/or step conditions of post-casting steps. For example, when a speed at which the aluminum alloy after casting is cooled increases, the size of a crystal grain in the aluminum alloy may decrease.
According to various embodiments, crystal grains of the aluminum alloy extruded material may have an average particle diameter of 100 µm to 300 µm, desirably, 150 µm to 300 µm. At least two crystal grains may be adjacent to each other at an edge and may form a grain boundary at the edge, and at least two adjacent crystal grains based on the grain boundary may have different potentials. According to various embodiments, a potential difference at an interface between at least two adjacent crystal grains in the aluminum alloy extruded material may range from 30 millivolts (mV) to 100 mV, and desirably, a potential difference between at least two crystal grains at a grain boundary may range from 30 mV to 50 mV. According to various embodiments, the aluminum alloy extruded material may include copper (Cu). According to various embodiments, the copper may be included in an amount of 0.03 wt% to 0.50 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of copper is less than 0.03 wt% based on the total weight of the aluminum alloy extruded material, the corrosion resistance may decrease due to an increase in a potential difference at a grain boundary in the aluminum alloy extruded material, and durability of the oxide film formed by performing the anodizing step may decrease. In addition, when the amount of copper exceeds 0.50 wt% based on the total weight of the aluminum alloy extruded material, the overall corrosion resistance of the aluminum alloy extruded material may be greatly reduced, and a color tone of the oxide film formed by performing the anodizing step may change to yellow, which may lead to a reduction in the exterior quality. For example, when copper is included in an amount of 0.03 wt% to 0.50 wt% based on the total weight of the aluminum alloy extruded material, a cut surface may be smoothly formed in a cutting step (e.g., a CNC cutting step) due to excellent corrosion resistance, a color tone of a surface may not change to yellow even though the oxide film is formed through the anodizing step, and the yield strength may be increased by 5 MPa to 10 MPa due to the enhanced rigidity.
According to various embodiments, the aluminum alloy extruded material may include manganese (Mn), and manganese may be included in an amount of 0.1 wt% to 0.3 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of manganese is greater than or equal to 0.1 wt% based on the total weight of the aluminum alloy extruded material, the surface gloss and gloss uniformity may be enhanced during the anodizing step by uniformly controlling the average particle diameter of crystal grains in the aluminum alloy extruded material. In addition, the rigidity may be enhanced due to a solid-solution strengthening effect caused by permeation of manganese into the aluminum alloy extruded material, and a reduction in the corrosion resistance due to the remaining excessive iron by forming a compound with iron may be mitigated. When the amount of manganese exceeds 0.3 wt% based on the total weight of the aluminum alloy extruded material, the surface gloss may be reduced as excessive manganese is dispersed.
According to various embodiments, the aluminum alloy extruded material may include silicon (Si), and silicon may be included in an amount of 0.01 wt% to 0.1 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of silicon is greater than or equal to 0.01 wt% based on the total weight of the aluminum alloy extruded material, silicon may react with excessive iron to mitigate a reduction in the corrosion resistance due to the remaining excessive iron. In addition, when the amount of silicon exceeds 0.1 wt% based on the total weight of the aluminum alloy extruded material, an average particle diameter of intermetallic compounds formed by a reaction with iron may exceed 10 µm, and the surface gloss may be greatly reduced by the intermetallic compounds dispersed on the surface.
According to various embodiments, the aluminum alloy extruded material may include iron (Fe), and the iron may be included in an amount of 0.01 wt% to 0.15 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of iron is greater than or equal to 0.01 wt% based on the total weight of the aluminum alloy extruded material, at least one of adhesion, seizure resistance, and/or frictional force to a mold during an extrusion step may be reduced. When the amount of iron exceeds 0.15 wt%, the surface gloss may be reduced by forming an intermetallic compound with a particle diameter of 10 µm or greater together with silicon or manganese, and machinability may be reduced during a cutting step (e.g., a CNC cutting step), so that a cut surface may not be smooth. According to various embodiments, the iron may be desirably included in an amount of 0.07 wt% or less based on the total weight of the aluminum alloy extruded material.
According to various embodiments, the aluminum alloy extruded material may include titanium (Ti), and the titanium may be included in an amount of 0.005 wt% to 0.03 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of titanium is greater than or equal to 0.005 wt% based on the total weight of the aluminum alloy extruded material, crystal grains in the aluminum alloy extruded material may be uniformly formed to have an average diameter of 300 µm or less, the surface gloss and/or gloss uniformity of the oxide film according to the anodizing step may be increased, and a crack may not occur during extrusion. According to various embodiments, when the amount of titanium exceeds 0.03 wt% based on the total weight of the aluminum alloy extruded material, a compound formed by excessive titanium may have various shapes (e.g., a linear shape) on the surface of the aluminum alloy extruded material. According to various embodiments, the aluminum alloy extruded material may include zirconium (Zr), and the zirconium may be included in an amount of 0.005 wt% to 0.03 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of zirconium is greater than or equal to 0.005 wt% based on the total weight of the aluminum alloy extruded material, crystal grains in the aluminum alloy extruded material may be uniformly formed to have an average diameter of 300 µm or less, the surface gloss and/or gloss uniformity of the oxide film according to the anodizing step may be increased, and a crack may not occur during extrusion. According to various embodiments, when the amount of zirconium exceeds 0.03 wt% based on the total weight of the aluminum alloy extruded material, a compound formed by excessive zirconium may have various shapes (e.g., a linear shape) on the surface of the aluminum alloy extruded material. According to various embodiments, the aluminum alloy extruded material may include chromium (Cr), and the chromium may be included in an amount of 0.0001 wt% to 0.03 wt% based on the total weight of the aluminum alloy extruded material. According to various embodiments, when the amount of chromium is greater than or equal to 0.0001 wt% based on the total weight of the aluminum alloy extruded material, the average diameter of the crystal grains may be maintained at 10 µm or less, the rigidity may increase, and internal stress corrosion cracking in the aluminum alloy extruded material may be mitigated. When the amount of chromium exceeds 0.03 wt%, the color tone of the surface may change (e.g., change to yellow) as the anodizing step is performed, thereby reducing the exterior quality. According to various embodiments, the aluminum alloy extruded material may include copper (Cu) and zinc (Zn), and the amount of copper and the amount of zinc may satisfy Equation 3 below. $0.003 \leq \frac{[Cu]}{[Zn]} \leq 0.375$
([Cu] corresponds to an amount (wt%) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn).)
According to various embodiments, a ratio of the amount of copper to the amount of zinc in the aluminum alloy extruded material may range from "0.003" to "0.375". When the ratio of the amount of copper to the amount of zinc is less than "0.003", the oxide film formed through the anodizing step may be easily detached due to a relatively large amount of zinc, and when the ratio of the amount of copper to the amount of zinc exceeds "0.375", the corrosion resistance may be greatly reduced due to a relatively large amount of copper, and the color tone may change (e.g., a yellowing phenomenon occurs) as the anodizing step is performed.
According to various embodiments, the aluminum alloy extruded material may include copper (Cu) and zinc (Zn), and the amount of copper and the amount of zinc may satisfy Equation 4 below. $\frac{[Cu]}{[Zn]} \geq 0.14 - \frac{0.782}{[Zn]}$
([Cu] corresponds to an amount (wt%) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn).)
According to various embodiments, in the aluminum alloy extruded material, the ratio of the amount of copper to the amount of zinc may be determined according to the amount of zinc. According to various embodiments, when zinc is excessively included in the aluminum alloy extruded material beyond a predetermined range, the oxide film formed by performing the anodizing step may be easily detached, and accordingly, copper may desirably be added together in a predetermined range. According to various embodiments, to prevent the oxide film from being detached, the ratio of the amount of copper to the amount of zinc may be set according to the amount of zinc in the aluminum alloy extruded material. According to various embodiments, the amount of copper and the amount of zinc in the aluminum alloy extruded material may satisfy Equation 4 described above. Based on the total weight of the aluminum alloy extruded material, zinc may be included in an amount of 5.85 wt% to 8.0 wt% and copper may be included in an amount of 0.03 wt% to 0.50 wt%.
According to various embodiments, the aluminum alloy extruded material may have a yield strength of 450 MPa or greater. According to various embodiments, a homogenization step through a heat treatment may be performed on the aluminum alloy extruded material, and the yield strength of the aluminum alloy extruded material may be 460 MPa or greater, 465 MPa or greater, 470 MPa or greater, 480 MPa or greater, 490 MPa or greater, 500 MPa or greater, 510 MPa or greater, 520 MPa or greater, 530 MPa or greater, or 540 MPa or greater. According to various embodiments, the aluminum alloy extruded material may have a surface hardness of 150 Hv or greater. The surface hardness may be measured according to a Vickers hardness measurement method. Specifically, the hardness may be measured by pressing an aluminum alloy extruded material using a pyramid-shaped diamond indenter in the form of a quadrangular pyramid having a face angle of 136° and by using a diagonal length of a concave portion of a pyramid shape formed by pressing the aluminum alloy extruded material. According to various embodiments, the surface hardness of the aluminum alloy extruded material may be 160 Hv or greater, 170 Hv or greater, 180 Hv or greater, 190 Hv or greater, 200 Hv or greater, or 210 Hv or greater.
An electronic device housing according to various embodiments may include an aluminum alloy extruded material according to an embodiment. For example, the aluminum alloy extruded material may be used as a housing of an electronic device including at least one of a mobile phone and/or a tablet computer. According to various embodiments, the aluminum alloy extruded material may be used to prepare a housing for an outer casing of a mobile phone (e.g., a smartphone) and tablet bottom chassis.
According to various embodiments, the aluminum alloy extruded material may have a surface gloss of 300 GU or greater measured according to ISO 2813. According to an embodiment, the aluminum alloy extruded material may be used for a housing (e.g., an exterior frame of the electronic device) of the electronic device to protect internal components and modules of the electronic device. According to an embodiment, the aluminum alloy extruded material may be glossy so that the exterior of the electronic device may be made aesthetic.
According to various embodiments, the surface gloss of the aluminum alloy extruded material may be measured according to ISO 2813, the standard of the International Organization for Standardization. According to ISO 2813, surface gloss of an uncolored specimen with a thickness of about 10 µm is measured, and an amount of light to be incident at 60° and reflected is measured to measure the surface gloss of the surface of the aluminum alloy extruded material.
According to various embodiments, the aluminum alloy extruded material may include aluminum (Al), zinc (Zn), and magnesium (Mg), and may have the surface gloss of 300 GU or greater measured according to ISO 2813.
According to various embodiments, the amount of zinc and the amount of magnesium may satisfy Equation 2 below. $2 \leq \frac{[Zn]}{[Mg]} \leq 4$
([Zn] corresponds to the amount (wt%) of zinc (Zn), and [Mg] corresponds to the amount (wt%) of magnesium (Mg).)
According to various embodiments, the aluminum alloy extruded material may further include an intermetallic compound including Zn₂Mg, and the intermetallic compound may have a diameter of 10 µm or less.
According to various embodiments, the aluminum alloy extruded material may include crystal grains having the average particle diameter of 100 µm to 300 µm, and a potential difference at an interface between at least two adjacent crystal grains may be in the range of 30 mV to 100 mV.
According to various embodiments, zinc may be present in an amount of 5.85 wt% to 8.0 wt%, and magnesium may be present in an amount of 2.0 wt% to 2.9 wt%.
According to various embodiments, the aluminum alloy extruded material may further include copper (Cu), and the copper may be included in an amount of 0.03 wt% to 0.50 wt%. According to various embodiments, the aluminum alloy extruded material may further include copper (Cu), and the amount of copper and the amount of zinc may satisfy Equation 3 below. $0.003 \leq \frac{[Cu]}{[Zn]} \leq 0.375$
([Cu] corresponds to an amount (wt%) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn).)
According to various embodiments, the aluminum alloy extruded material may further include copper (Cu), and the amount of copper and the amount of zinc may satisfy Equation 4 below. $\frac{[Cu]}{[Zn]} \geq 0.14 - \frac{0.782}{[Zn]}$
([Cu] corresponds to an amount (wt%) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn).)
According to various embodiments, the aluminum alloy extruded material may further include manganese (Mn), silicon (Si), iron (Fe), titanium (Ti), zirconium (Zr), and chromium (Cr), manganese may be present in an amount of 0.1 wt% to 0.3 wt%, silicon may be present in an amount of 0.01 wt% to 0.1 wt%, iron may be present in an amount of 0.01 wt% to 0.15 wt%, titanium may be present in an amount of 0.005 wt% to 0.03 wt%, zirconium may be present in an amount of 0.005 wt% to 0.03 wt%, and chromium may be present in an amount of 0.0001 wt% to 0.03 wt%.
According to various embodiments, the aluminum alloy extruded material may further include copper (Cu), manganese (Mn), silicon (Si), iron (Fe), titanium (Ti), zirconium (Zr), and chromium (Cr). Zinc may be present in an amount of 5.85 wt% to 8.0 wt, magnesium may be present in an amount of 2.0 wt% to 2.9 wt%, copper may be present in an amount of 0.03 wt% to 0.50 wt%, manganese may be present in an amount of 0.1 wt% to 0.3 wt%, silicon may be present in an amount of 0.01 wt% to 0.1 wt, iron may be present in an amount of 0.01 wt% to 0.15 wt%, titanium may be present in an amount of 0.005 wt% to 0.03 wt%, zirconium may be present in an amount of 0.005 wt% to 0.03 wt%, chromium may be present in an amount of 0.0001 wt% to 0.03 wt%, and aluminum may account for the remainder. According to various embodiments, the aluminum alloy extruded material may have a yield strength of 450 MPa or greater.
According to various embodiments, the aluminum alloy extruded material may have a surface hardness of 150 Hv or greater.
According to various embodiments, the aluminum alloy extruded material may have the surface gloss of 300 GU or greater measured according to ISO 2813.
According to various embodiments, the electronic device housing may include an aluminum alloy extruded material according to various embodiments.
FIG. 2 is a flowchart of steps of a method of preparing an aluminum alloy extruded material according to various embodiments.
Referring to FIG. 2, the method of preparing the aluminum alloy extruded material may include step 210 of preparing an aluminum metal, step 220 of forming an aluminum alloy by melting the aluminum metal and adding metal elements using zinc and magnesium, step 230 of heating and extruding the aluminum alloy, and step 240 of performing a heat treatment on the aluminum alloy.
According to various embodiments, to form an aluminum alloy, aluminum or a master alloy may be prepared and melted. For example, metal elements including zinc and magnesium may be added to a molten metal obtained by melting the aluminum alloy by heating pure aluminum (AI) at a temperature of 850°C or higher, to form an alloy. The metal elements may be simultaneously or sequentially added, and may be added by adding a metal flux containing a large amount of metal elements to molten aluminum.
According to various embodiments, the metal elements added in step 220 of forming the aluminum alloy may further include at least one of copper (Cu), manganese (Mn), silicon (Si), iron (Fe), titanium (Ti), zirconium (Zr) and/or chromium (Cr). According to various embodiments, a characteristic of the aluminum alloy extruded material obtained after an extrusion step may be determined according to the amount of metal elements added in step 220 of forming the aluminum alloy.
According to various embodiments, zinc (Zn) may be included in an amount of 5.85 wt% to 8.0 wt% based on the total weight of the aluminum alloy. Zinc may be bonded to magnesium in the aluminum alloy to form a Zn₂Mg strengthening phase. When the amount of zinc is less than 5.85 wt%, yield strength of the aluminum alloy formed by extrusion may decrease, and when the amount of zinc exceeds 8 wt%, corrosion resistance may decrease, and a plurality of segregations and a plurality of compounds containing zinc may be present in the aluminum alloy extruded material. For example, when the amount of zinc is less than 5.85 wt% based on the total weight of the aluminum alloy, the yield strength of the aluminum alloy extruded material may be less than 450 MPa, and when the amount of zinc exceeds 8 wt%, gloss of a surface of an oxide film formed by performing an anodizing step may be reduced to be less than 300 GU, and surface roughening may occur.
According to various embodiments, magnesium (Mg) may be included in an amount of 2 wt% to 2.9 wt% based on the total weight of the aluminum alloy. When the amount of magnesium is less than 2 wt% based on the total weight of the aluminum alloy, the yield strength of the aluminum alloy extruded material formed by extrusion may decrease, and when the amount of magnesium exceeds 2.9 wt%, extrudability may be reduced due to a low solidus temperature of the aluminum alloy extruded material. For example, when the amount of magnesium is less than 2 wt% based on the total weight of the aluminum alloy, the yield strength may be less than 450 MPa, and when the amount of magnesium exceeds 2.9 wt%, it may be difficult to apply a high extrusion temperature, and accordingly an extrusion speed may decrease, a crack may occur, and gloss of a surface may be reduced to be less than 300 GU after the oxide film is formed through the anodizing step.
According to various embodiments, copper (Cu) may be included in an amount of 0.03 wt% to 0.50 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of copper is less than 0.03 wt% based on the total weight of the aluminum alloy, the corrosion resistance may decrease due to an increase in a potential difference at a grain boundary in the aluminum alloy extruded material, and durability of the oxide film formed by performing the anodizing step may decrease. In addition, when the amount of copper exceeds 0.50 wt% based on the total weight of the aluminum alloy, the overall corrosion resistance of the aluminum alloy extruded material may be greatly reduced, and a color tone of the oxide film formed by performing the anodizing step may change to yellow, which may lead to a reduction in the exterior quality. For example, when copper is included in an amount of 0.03 wt% to 0.50 wt% based on the total weight of the aluminum alloy, a cut surface may be smoothly formed in a cutting step (e.g., a CNC cutting step) due to excellent corrosion resistance, a color tone of a surface may not change to yellow even though the oxide film is formed through the anodizing step, and the yield strength may be increased by 5 MPa to 10 MPa due to the enhanced rigidity.
According to various embodiments, manganese (Mn) may be included in an amount of 0.1 wt% to 0.3 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of manganese is greater than or equal to 0.1 wt% based on the total weight of the aluminum alloy, the surface gloss and gloss uniformity may be enhanced during the anodizing step by uniformly controlling the average particle diameter of crystal grains in the aluminum alloy. In addition, the rigidity may be enhanced due to a solid-solution strengthening effect caused by permeation of manganese into the aluminum alloy extruded material, and a reduction in the corrosion resistance due to the remaining excessive iron by forming a compound with iron may be mitigated. When the amount of manganese exceeds 0.3 wt% based on the total weight of the aluminum alloy, the surface gloss may be reduced as excessive manganese is dispersed.
According to various embodiments, silicon (Si) may be included in an amount of 0.01 wt% to 0.1 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of silicon is greater than or equal to 0.01 wt% based on the total weight of the aluminum alloy, silicon may react with excessive iron to mitigate a reduction in the corrosion resistance due to the remaining excessive iron. In addition, when the amount of silicon exceeds 0.1 wt% based on the total weight of the aluminum alloy, an average particle diameter of intermetallic compounds formed by a reaction with iron may exceed 10 µm, and the surface gloss may be greatly reduced by the intermetallic compounds dispersed on the surface.
According to various embodiments, iron (Fe) may be included in an amount of 0.01 wt% to 0.15 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of iron is greater than or equal to 0.01 wt% based on the total weight of the aluminum alloy, at least one of adhesion, seizure resistance, and/or frictional force to a mold during an extrusion step may be reduced. When the amount of iron exceeds 0.15 wt%, the surface gloss may be reduced by forming an intermetallic compound with a particle diameter of 10 µm or greater together with silicon or manganese, and machinability may be reduced during a cutting step (e.g., a CNC cutting step), so that a cut surface may not be smooth. According to various embodiments, iron may desirably be included in an amount of 0.07 wt% or less based on the total weight of the aluminum alloy.
According to various embodiments, titanium (Ti) may be included in an amount of 0.005 wt% to 0.03 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of titanium is greater than or equal to 0.005 wt% based on the total weight of the aluminum alloy, crystal grains in the aluminum alloy extruded material may be uniformly formed to have an average diameter of 300 µm or less, the surface gloss and/or gloss uniformity of the oxide film according to the anodizing step may be increased, and a crack may not occur during extrusion. According to various embodiments, when the amount of titanium exceeds 0.03 wt% based on the total weight of the aluminum alloy, a compound formed by excessive titanium may have various shapes (e.g., a linear shape) on the surface of the aluminum alloy extruded material.
According to various embodiments, zirconium (Zr) may be included in an amount of 0.005 wt% to 0.03 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of zirconium is greater than or equal to 0.005 wt% based on the total weight of the aluminum alloy, crystal grains in the aluminum alloy extruded material may be uniformly formed to have an average diameter of 300 µm or less, the surface gloss and/or gloss uniformity of the oxide film according to the anodizing step may be increased, and a crack may not occur during extrusion. According to various embodiments, when the amount of zirconium exceeds 0.03 wt% based on the total weight of the aluminum alloy, a compound formed by excessive zirconium may have various shapes (e.g., a linear shape) on the surface of the aluminum alloy extruded material.
According to various embodiments, chromium (Cr) may be included in an amount of 0.0001 wt% to 0.03 wt% based on the total weight of the aluminum alloy. According to various embodiments, when the amount of chromium is greater than or equal to 0.0001 wt% based on the total weight of the aluminum alloy extruded material, the average diameter of the crystal grains may be maintained at 10 µm or less, the rigidity may increase, and internal stress corrosion cracking in the aluminum alloy extruded material may be mitigated. When the amount of chromium exceeds 0.03 wt%, the color tone of the surface may change (e.g., change to yellow) as the anodizing step is performed, thereby reducing the exterior quality. According to various embodiments, in step 220 of forming the aluminum alloy, a billet for extrusion may be formed, and a diameter of the billet may range from 4 inches to 10 inches. According to various embodiments, after step 220 of forming the aluminum alloy, a step of performing a homogenizing heat treatment on the aluminum alloy may be further performed. According to various embodiments, the step of performing the homogenizing heat treatment may be performed for homogenization by equilibrating a concentration gradient of metal elements in the extruded aluminum alloy and may be performed to make nonuniform microstructures uniform as a whole. In the step of performing the homogenizing heat treatment, heating may be performed at a high temperature (e.g., 450°C to 650°C, desirably 500°C to 650°C, below the solvus temperature of the aluminum alloy) for several hours or less, for example, a period of 30 hours or less.
According to various embodiments, step 230 of extruding the aluminum alloy may be performed simultaneously with heating. According to various embodiments, step 230 of extruding the aluminum alloy may be performed by inserting the aluminum alloy into an extruder, and may be performed simultaneously with heating to reduce extrusion stress. According to various embodiments, the temperature of the aluminum alloy may further rise due to extrusion friction in the extruder during extruding. The extrusion speed of the alloy and/or a temperature at which the aluminum alloy is inserted into the extruder may be controlled, to control heating so that the aluminum alloy may be prevented from being heated up to solidus temperature or greater during extrusion of the aluminum alloy. According to various embodiments, a cross-sectional area of the aluminum alloy may be reduced by 90% or greater through step 230 of extruding the aluminum alloy.
According to various embodiments, step 240 of performing the heat treatment on the extruded aluminum alloy may be performed at a temperature of 210°C or less. According to various embodiments, step 240 of performing the heat treatment may be performed at a temperature of 200°C or less, 190°C or less, 180°C or less, or 170°C or less. According to various embodiments, the aluminum alloy extruded through step 240 of performing the heat treatment may be formed as an aluminum alloy extruded material, and step 240 of performing the heat treatment may be performed for 1 hour to 48 hours. According to various embodiments, as an intermetallic compound (e.g., Zn₂Mg) is precipitated through step 240 of performing the heat treatment, the rigidity of the aluminum alloy extruded material may be greatly enhanced.
FIG. 3 is a flowchart of a method of preparing an aluminum alloy extruded material according to various embodiments.
Referring to FIG. 3, the method of preparing the aluminum alloy extruded material may include step 310 (e.g., step 210 of FIG. 2) of preparing an aluminum metal, step 320 (e.g., step 220 of FIG. 2) of forming an aluminum alloy by melting the aluminum metal and adding metal elements using zinc and magnesium, step 330 (e.g., step 230 of FIG. 2) of heating and extruding the aluminum alloy, step 340 (e.g., step 240 of FIG. 2) of performing a heat treatment on the aluminum alloy, and step 350 of anodizing an aluminum alloy extruded material formed through the above steps.
According to various embodiments, step 350 of anodizing the aluminum alloy extruded material may be performed to form an oxide film on a surface of the aluminum alloy extruded material. Prior to step 350 of anodizing the aluminum alloy extruded material, a cutting step (not shown) for the aluminum alloy extruded material to have a specific shape and form may be further included. The cutting step may be performed, for example, through CNC cutting. For example, through the cutting step, the aluminum alloy extruded material may have a shape and/or form to be used as a housing of an electronic device (e.g., a mobile electronic device, a laptop, a portable terminal, etc.).
According to various embodiments, an oxide film may be formed on the surface of the aluminum alloy extruded material through step 350 of anodizing the aluminum alloy extruded material so that the surface may be treated. Step 350 of anodizing the aluminum alloy extruded material may be performed by immersing the aluminum alloy extruded material in a solution containing at least one of sulfuric acid, nitric acid, phosphoric acid, oxalic acid, and chromic acid under a current density of 0.5 A/dm³ to 2 A/dm³.
Hereinafter, the present disclosure will be described in more detail with reference to examples and comparative examples.
However, the following examples are only for illustrating the present disclosure, and the present disclosure is not limited to the following examples.

Examples and comparative examples

Aluminum alloy extruded materials may be prepared by adding various metal elements to pure aluminum. Compositions of aluminum alloys of examples and comparative examples may be shown in Table 1 below by adding different amounts of metal elements based on the total weight of the aluminum alloy extruded material.

[Table 1]

Item	Zn [wt%]	Mg [wt%]	Cu [wt%]	Mn [wt%]	Si [wt%]	Fe [wt%]	Ti [wt%]	Zr [wt%]	Cr [wt%]	Al [wt%]
Example 1	5.85	2.0	0.03	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Example 2	5.85	2.9	0.03	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Example 3	5.85	2.9	0.50	0.3	0.1	0.15	0.03	0.03	0.03	Remainder
Example 4	6.1	2.0	0.06	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Example 5	6.1	2.1	0.03	0.15	0.06	0.07	0.015	0.015	0.015	Remainder
Example 6	6.1	2.9	0.50	0.3	0.1	0.15	0.03	0.03	0.03	Remainder
Example 7	6.3	2.3	0.03	0.15	0.06	0.07	0.015	0.015	0.015	Remainder
Example 8	7.0	2.0	0.03	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Example 9	7.0	2.9	0.50	0.3	0.1	0.15	0.03	0.03	0.03	Remainder
Example 10	8.0	2.0	0.03	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Example 11	8.0	2.9	0.50	0.3	0.1	0.15	0.03	0.03	0.03	Remainder
Comparative Example 1	5.8	2.0	0.03	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Comparative Example 2	8.2	2.0	0.03	0.1	0.01	0.01	0.005	0.005	0.0001	Remainder
Comparative Example 3	8.3	2.9	0.50	0.3	0.1	0.15	0.03	0.03	0.03	Remainder

Heat treatments may be performed on aluminum alloys of Examples 1 to 11 and Comparative Examples 1 to 3 according to Table 1 at 210°C, to homogenize each of the aluminum alloys. An electronic device housing having an oxide film formed on a surface thereof may be manufactured as an electronic device housing through a CNC cutting step and an anodizing step of aluminum alloy extruded materials formed according to the examples and comparative examples.

Experimental example

For the aluminum alloy extruded materials according to Examples 1 to 11 and Comparative Examples 1 to 3, yield strength, Vickers surface hardness, and gloss of a surface of an oxide film may be measured. The yield strength, surface hardness and surface gloss of the aluminum alloy extruded materials may be measured according to KS D 8301, and the results may be shown in Table 2 below.

[Table 2]

Item	Yield strength [MPa]	Hardness [Hv]	Surface gloss [GU]
Example 1	451	160	408
Example 2	504	189	400
Example 3	517	195	390
Example 4	460	169	381
Example 5	465	172	381
Example 6	531	205	365
Example 7	498	179	348
Example 8	507	187	330
Example 9	533	210	346
Example 10	519	202	318
Example 11	549	215	325
Comparative Example 1	448	157	408
Comparative Example 2	519	204	280
Comparative Example 3	588	220	220

In addition, a cross section of an aluminum alloy extruded material according to an embodiment may be observed with a microscope, as shown in FIG. 4. FIG. 4 is an image obtained by capturing a cross section of an aluminum alloy extruded material according to an embodiment.
Referring to FIG. 4, the aluminum alloy extruded material may include a plurality of grain structures. Crystal grains may have the same size or different sizes, and have an average particle diameter of 100 µm to 300 µm. In addition, an intermetallic compound may be formed within crystal grains or at a grain boundary. An intermetallic compound (e.g., Zn₂Mg) may be formed by binding of excessive metal elements (e.g., magnesium, zinc, iron, silicon, manganese, etc.) other than aluminum. In addition, the intermetallic compound may be in the form of small black grains, for example, needles. The average particle diameter of intermetallic compounds may be 100 µm to 300 µm, desirably 150 µm to 300 µm. In addition, one crystal grain and another adjacent crystal grain may form a grain boundary that is an adjacent boundary, and at least two adjacent crystal grains based on the grain boundary may have different potentials.
Whether oxide films formed on surfaces of the aluminum alloy extruded materials according to Example 1 and Comparative Example 1 are detached may be tested. Adhesion of an oxide film may be observed based on whether the oxide film is detached after the oxide film is scratched with a knife blade and attached and detached several times using a tape according to ISO 2409 or ASTM D3359-17.
The electronic device according to various embodiments disclosed herein may be one of various types of electronic devices. The electronic devices may include, for example, a portable communication device (e.g., a smartphone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, or a home appliance. According to an embodiment of the disclosure, the electronic device is not limited to those described above.
It should be appreciated that various embodiments of the disclosure and the terms used therein are not intended to limit the technological features set forth herein to particular embodiments and include various changes, equivalents, or replacements for a corresponding embodiment. With regard to the description of the drawings, similar reference numerals may be used to refer to similar or related elements. It is to be understood that a singular form of a noun corresponding to an item may include one or more of the things, unless the relevant context clearly indicates otherwise. As used herein, each of such phrases as "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B, or C", may include any one of, or all possible combinations of the items enumerated together in a corresponding one of the phrases. As used herein, such terms as "1^st" and "2^nd," or "first" and "second" may be used to simply distinguish a corresponding component from another, and does not limit the components in other aspect (e.g., importance or order). It is to be understood that if a component (e.g., a first component) is referred to, with or without the term "operatively" or "communicatively", as "coupled with", "coupled to", "connected with", or "connected to" another component (e.g., a second component), it means that the component may be coupled with the other component directly (e.g., by wire), wirelessly, or via a third component.
As used in connection with various embodiments of the disclosure, the term "module" may include a unit implemented in hardware, software, or firmware, and may interchangeably be used with other terms, for example, "logic", "logic block", "part", or "circuitry". A module may be a single integral component, or a minimum unit or part thereof, adapted to perform one or more functions. For example, according to an embodiment, the module may be implemented in a form of an application-specific integrated circuit (ASIC).
Various embodiments as set forth herein may be implemented as software (e.g., the program 140) including one or more instructions that are stored in a storage medium (e.g., an internal memory 136 or an external memory 138) that is readable by a machine (e.g., the electronic device 101). For example, a processor (e.g., the processor 120) of the machine (e.g., the electronic device 101) may invoke at least one of the one or more instructions stored in the storage medium, and execute it. This allows the machine to be operated to perform at least one function according to the at least one instruction invoked. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory" simply means that the storage medium is a tangible device, and does not include a signal (e.g., an electromagnetic wave), but this term does not differentiate between where data is semi-permanently stored in the storage medium and where the data is temporarily stored in the storage medium.
According to an embodiment, a method according to various embodiments disclosed herein may be included and provided in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or be distributed (e.g., downloaded or uploaded) online via an application store (e.g., PlayStore^™), or between two user devices (e.g., smartphones) directly. If distributed online, at least part of the computer program product may be temporarily generated or at least temporarily stored in the machine-readable storage medium, such as a memory of the manufacturer's server, a server of the application store, or a relay server.
According to various embodiments, each component (e.g., a module or a program) of the above-described components may include a single entity or multiple entities, and some of the multiple entities may be separately disposed in different components. According to various embodiments, one or more of the above-described components or operations may be omitted, or one or more other components or operations may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, the integrated component may still perform one or more functions of each of the plurality of components in the same or similar manner as they are performed by a corresponding one of the plurality of components before the integration. According to various embodiments, operations performed by the module, the program, or another component may be carried out sequentially, in parallel, repeatedly, or heuristically, or one or more of the operations may be executed in a different order or omitted, or one or more other operations may be added.

Claims

An aluminum alloy extruded material comprising:
aluminum (Al); zinc (Zn); magnesium (Mg); and copper (Cu),

wherein an amount of copper and an amount of zinc satisfy Equation 1 below, $[Cu] \geq 0.14 [Zn] - 0.782$

([Cu] corresponds to an amount (% by weight (wt%)) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn)).
The aluminum alloy extruded material of claim 1, wherein the amount of zinc and an amount of magnesium satisfy Equation 2 below, $2 \leq \frac{[Zn]}{[Mg]} \leq 4$
([Zn] corresponds to the amount (wt%) of zinc (Zn), and [Mg] corresponds to the amount (wt%) of magnesium (Mg)).
The aluminum alloy extruded material of claim 1, further comprising:
an intermetallic compound including Zn₂Mg,

wherein the intermetallic compound has a diameter of 10 micrometers (µm) or less.
The aluminum alloy extruded material of claim 1, wherein
the aluminum alloy extruded material comprises crystal grains having an average particle diameter of 100 µm to 300 µm, and

a potential difference at an interface between at least two adjacent crystal grains is in a range of 30 millivolts (mV) to 100 mV.
The aluminum alloy extruded material of claim 1, wherein
the zinc is present in an amount of 5.85 wt% to 8.0 wt%, and

the magnesium is present in an amount of 2.0 wt% to 2.9 wt%.
The aluminum alloy extruded material of claim 1, wherein the copper is present in an amount of 0.03 wt% to 0.50 wt%.
The aluminum alloy extruded material of claim 1, wherein the amount of copper and the amount of zinc satisfy Equation 3 below, $0.003 \leq \frac{[Cu]}{[Zn]} \leq 0.375$
([Cu] corresponds to an amount (wt%) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn).)
The aluminum alloy extruded material of claim 1, wherein the amount of copper and the amount of zinc satisfy Equation 4 below, $\frac{[Cu]}{[Zn]} \geq 0.14 - \frac{0.782}{[Zn]}$
([Cu] corresponds to an amount (wt%) of copper (Cu), and [Zn] corresponds to an amount (wt%) of zinc (Zn)).
The aluminum alloy extruded material of claim 1, further comprising:
manganese (Mn); silicon (Si); iron (Fe); titanium (Ti); zirconium (Zr); and chromium (Cr),

wherein the manganese is present in an amount of 0.1 wt% to 0.3 wt%,

wherein the silicon is present in an amount of 0.01 wt% to 0.1 wt%,

wherein the iron is present in an amount of 0.01% to 0.15 wt%,

wherein the titanium is present in an amount of 0.005 wt% to 0.03 wt%,

wherein the zirconium is present in an amount of 0.005 wt% to 0.03 wt%, and

wherein the chromium is present in an amount of 0.0001 wt% to 0.03 wt%.
The aluminum alloy extruded material of claim 1, further comprising:
manganese (Mn); silicon (Si); iron (Fe); titanium (Ti); zirconium (Zr); and chromium (Cr),

wherein the zinc is present in an amount of 5.85 wt% to 8.0 wt%,

wherein the magnesium is present in an amount of 2.0 wt% to 2.9 wt%,

wherein the copper is present in an amount of 0.03 wt% to 0.50 wt%,

wherein the manganese is present in an amount of 0.1 wt% to 0.3 wt%,

wherein the silicon is present in an amount of 0.01 wt% to 0.1 wt%,

wherein the iron is present in an amount of 0.01% to 0.15 wt%,

wherein the titanium is present in an amount of 0.005 wt% to 0.03 wt%,

wherein the zirconium is present in an amount of 0.005 wt% to 0.03 wt%,

wherein the chromium is present in an amount of 0.0001 wt% to 0.03 wt%, and

wherein the aluminum accounts for the remainder.
The aluminum alloy extruded material of claim 1, wherein the aluminum alloy extruded material has a yield strength of 450 megapascals (MPa) or greater.
The aluminum alloy extruded material of claim 1, wherein the aluminum alloy extruded material has a surface hardness of 150 Hv or greater.
The aluminum alloy extruded material of claim 1, wherein the aluminum alloy extruded material has a surface gloss of 300 GU or greater measured according to ISO 2813.
An electronic device housing comprising the aluminum alloy extruded material of claim 1.