CN114525426A

CN114525426A - Preparation method of novel high-temperature oxidation resistant multi-element copper alloy

Info

Publication number: CN114525426A
Application number: CN202210134545.6A
Authority: CN
Inventors: 沈涛; 朱永福
Original assignee: Tongling Fuxiang Copper Based Material Technology Co ltd; Jilin University
Current assignee: Tongling Fuxiang Copper Based Material Technology Co ltd; Jilin University
Priority date: 2022-02-14
Filing date: 2022-02-14
Publication date: 2022-05-24

Abstract

The invention discloses a preparation method of a novel high-temperature oxidation resistant multi-element copper alloy, which comprises the steps of adding trace non-metal silicon elements and oxygen group elements (S, Se and Te) into a pure copper raw material to form a three-element copper alloy, carrying out pre-annealing treatment in a protective atmosphere, and carrying out segregation of the non-metal elements to the surface of the alloy through an annealing process to obtain stable SiO with a certain thickness₂Protective film coverA Cu-S (Cu-Se, Cu-Te) segregation layer of the cap, thereby forming a double-layer protection mechanism. The high-temperature oxidation resistant multi-element copper alloy provided by the invention obviously enhances the oxidation resistance of a metal copper material, can ensure that a copper consumable material product is not easily oxidized under the condition of high-temperature air, enlarges the application range of the alloy, prolongs the quality guarantee time of the alloy, has simple and easily repeated operation flow, has simple and easily-achieved required conditions, can meet the industrial production requirement of the copper consumable material, has environmental protection requirement in the manufacturing process, is green and pollution-free, and has important significance for the process development of modern metal materials.

Description

Preparation method of novel high-temperature oxidation resistant multi-element copper alloy

Technical Field

The invention relates to the technical field of antioxidant treatment of industrial metal consumables, in particular to a preparation method of a novel high-temperature oxidation resistant multi-element copper alloy.

Background

Copper is a soft, malleable, ductile metal. It has very extensive attributes and immeasurable value in the socioeconomic development. It is widely used due to its excellent electrical conductivity, thermal conductivity and excellent workability. More than half of copper is mainly used in electronic power and related industries, such as manufacturing electrical machinery, electrical equipment, transmission cables, integrated circuits, and the like. However, in the above applications, copper articles tend to suffer from similar oxidation corrosion. For example, the packaging process of integrated circuits is mostly performed at a high temperature of about 400 ℃, and the resulting oxidation problem of copper connecting wires is inevitable. Therefore, it is necessary to investigate the improvement of the high temperature oxidation resistance of metallic copper.

Addition of alloying elements is a common method of improving the oxidation resistance of copper. Currently, nearly one hundred types of copper alloys with excellent properties, such as copper-titanium, copper-zirconium, copper-iron, etc., to which metal elements are added have been developed. However, the metallic alloy elements reinforced copper alloy still has a relatively obvious oxidation phenomenon at high temperature, which indicates that the capability of improving the oxidation resistance is weak, and the wide application of the copper alloy is limited. Therefore, there is a need for the research of copper alloys doped with non-metallic elements. In the previous studies, the enhancement of the high-temperature oxidation of metallic copper by the chalcogen elements S, Se, Te and Si was confirmed. In the method for improving the corrosion resistance of copper by adding the oxygen group alloy (patent number ZL201010101728.5), the trace oxygen group element doping can obviously improve the oxidation resistance of metal copper, so that the copper alloy is not easily oxidized in a high-temperature working environment, but the method only slows down the oxidation rate, and the copper material can still be seriously oxidized after being oxidized for a long time.

In addition, the invention relates to a method for improving the oxidation resistance of copper by using a self-generated non-metal oxide composite film (patent No. ZL201911044881.6)The Si element of the copper-silicon binary alloy is added to prepare the copper-silicon alloy, and the known copper-silicon binary alloy can form stable and compact single-layer protective SiO on the surface of a substrate when being subjected to high-temperature pre-annealing treatment₂And (5) attaching the film. However, the heat treatment conditions of the invention are harsh, the required heat treatment temperature needs to be over 800 ℃, and the annealing time needs to be 24 hours, so that the generated protective film can be ensured to be compact and uniform, and the production cost is overhigh.

Disclosure of Invention

1. Technical problem to be solved

The invention aims to solve the problems that in the prior art, the heat treatment condition is harsh, the required heat treatment temperature needs to be more than 800 ℃, the annealing time needs to be 24 hours, the generated protective film can be guaranteed to be compact and uniform, and the production cost is overhigh, and provides a novel preparation method of the high-temperature oxidation resistant multi-element copper alloy.

2. Technical scheme

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a novel high-temperature oxidation resistant multi-element copper alloy comprises the following steps:

step 1: mixing and smelting high-purity silicon particles and high-purity granular oxygen group (S, Se and Te) element raw materials, wherein the concentration of Si and oxygen group elements (S, Se and Te) in the alloy is 0.05-1 wt%, and the mass fraction of copper is 99.9-98 wt%;

step 2: putting materials required for smelting in a groove in a vacuum smelting furnace, and using a titanium ingot as a standard deoxidizing sample; then, the gas is introduced and discharged, and the furnace body is pumped to 10^-1Low vacuum Pa, introducing high-purity argon, repeatedly washing with gas for more than 5 times to minimize oxygen concentration, and pumping to 10 deg.C^-4The method comprises the following steps of (1) exhausting oxygen in a smelting furnace in a high vacuum environment of Pa, and finally introducing argon to balance atmospheric pressure to ensure that the whole smelting process is in an argon protective environment;

and step 3: before alloy smelting, firstly, repeatedly smelting a titanium ingot, and deoxidizing for more than 30 seconds each time; after smelting a titanium ingot, smelting the mixed material, and smelting each surface of each sample for 30s for 2-4 times to obtain an alloy product with uniform components and excellent performance;

and 4, step 4: polishing the alloy ingot obtained by smelting with abrasive paper, and then sequentially putting the alloy ingot into acetone and alcohol for ultrasonic cleaning to remove impurities; then, putting the alloy into electrolyte for electrolytic polishing, ultrasonically cleaning the alloy after electrolytic polishing by using ethanol and deionized water, and finally drying the alloy by using a blower with cold air;

and 5: pre-annealing the treated alloy in a tubular furnace filled with protective atmosphere gas, wherein the annealing temperature is 500-800 ℃; keeping the temperature in the annealing furnace for 240-1440 min, slowly cooling to 200 ℃ by program temperature control, cooling to room temperature along with the furnace, introducing protective atmosphere in the whole heat treatment process, wherein the gas flow rate is 50cm³/min。

Preferably, in the step 1, the raw materials Si and S (Se and Te) are both in small particles, the purity is 99.99%, the use of powdery raw materials is avoided, and dust aggregation in the smelting process is prevented from influencing the alloy performance; avoid using blocky raw materials, prevent that the alloy from smelting unevenly.

Preferably, in the step 3, during the smelting process of the mixture, the smelting furnace is started to electromagnetically stir, or the copper mixture is manually turned over through a metal spoon in the smelting furnace, and after each turning over, the titanium ingot needs to be smelted again, so that oxygen escaped due to the movement of the metal spoon is removed.

Preferably, in the step 4, the copper alloy is sequentially subjected to mechanical grinding and polishing by 400-sand 7000-mesh sand paper; the electrolyte is a mixed solution of phosphoric acid and ethanol, a mega-signal constant current source is adopted, the output current is 0.5-2A, the voltage is 3-5V, a copper alloy sample is placed into an anode, copper sheets are placed into the left side and the right side of the copper alloy sample as cathodes, a preset current is introduced, and the polishing time is 1-2 min.

Preferably, in the step 5, the program temperature control and temperature reduction speed is set to be 1-2 ℃/min, and the furnace cooling speed is 5-8 ℃/min.

Preferably, in step 5, the protective atmosphere may be high-purity hydrogen, high-purity argon, or a mixture thereof in a certain ratio.

3. Advantageous effects

Compared with the prior art, the invention has the advantages that:

(1) the high-temperature oxidation resistant multi-element copper alloy provided by the invention obviously enhances the oxidation resistance of the metal copper material, can ensure that a copper consumption material product is not easily oxidized under the condition of high-temperature air, expands the application range of the alloy and prolongs the quality guarantee time of the alloy. The used materials are large in earth reserves, cheap and easily available, the operation flow is simple and easy to repeat, the required conditions are simple and easy to achieve, the industrial production requirements of copper consumables can be met, the manufacturing process meets the environmental protection requirements, and the method is green and pollution-free and has important significance for the process development of modern metal materials.

(2) In the invention, trace non-metal silicon element and oxygen group element (S, Se, Te) are added into pure copper raw material to form ternary copper alloy, pre-annealing treatment is carried out in protective atmosphere, non-metal element is segregated to the surface of the alloy through annealing process, and stable SiO with certain thickness₂The Cu-S (Cu-Se, Cu-Te) segregation layer covered by the protective film inhibits the oxidation corrosion of copper caused by the diffusion of oxygen into the copper material in the working environment, not only retains the protection capability of the Se layer, but also promotes the segregation of Si due to the existence of Se, thereby obviously improving the integral oxidation resistance of the metal copper.

(3) In the previous invention, the single-layer protective oxide film formed by pre-annealing the Cu-Si binary alloy has higher forming temperature and time, and the protective film is more sensitive to the change of annealing conditions. The alloy is pre-annealed, the Cu-S (Cu-Se, Cu-Te) lattice distortion is beneficial to the diffusion of Si, so that SiO₂The time and temperature requirements for film formation are greatly reduced.

(4) In the Cu-M segregation phase of the alloy according to the present invention, SiO, in which silicon is preferentially oxidized, is formed as compared with a protection mechanism in which only inclusions are segregated to the surface of a metal such as a binary Cu-S (Cu-Se, Cu-Te) alloy₂The film is covered, and the protection effect is obviously enhanced. After the alloy is subjected to a pretreatment process, double-layer protection is formed, the oxidation resistance effect is stronger, and the alloy can play a better strengthening role while saving the cost.

Drawings

FIG. 1 is a thermogravimetric plot of a copper alloy provided in accordance with examples 1-3 of the present invention;

FIG. 2 is a graph of XPS etching element percentage after annealing Cu-Se-Si alloy;

FIG. 3 is an XPS analysis of a surface Si 2p orbital of an annealed Cu-Se-Si alloy;

FIG. 4 is an XPS analysis of the O1s orbital at the surface of an annealed Cu-Se-Si alloy;

FIG. 5 is an XPS analysis of the Se 3d orbital at 1200s etching of annealed Cu-Se-Si alloys;

FIG. 6 is a surface SEM representation and elemental distribution diagram of a Cu-Se-Si alloy obtained in example 6 of the present invention;

FIG. 7 is a surface SEM representation and elemental distribution diagram of a Cu-Se-Si alloy obtained in example 7 of the present invention;

FIG. 8 is a surface SEM representation of the Cu-Se-Si alloy obtained in example 2 of the present invention;

FIG. 9 is a SEM representation of the surface of a Cu-Se-Si alloy obtained in example 2 of the present invention oxidized at 400 ℃ for 2h under air conditions;

FIG. 10 is a cross-sectional SEM representation and elemental distribution diagram of a Cu-Se-Si alloy obtained in example 6 of the present invention;

FIG. 11 is a macroscopic representation of the pre-annealed Cu-Se-Si alloy obtained in example 3 of the present invention after oxidation for 24 hours at 400 ℃ in air, compared to pure copper annealed and non-annealed Cu-Se-Si alloy under the same conditions.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Example 1:

step 1: mixing and smelting high-purity silicon particles and high-purity granular oxygen group (S, Se, Te) element raw materials, wherein the concentration of Si and the oxygen group element (S, Se, Te) in the alloy is 0.05-1 wt%, and the mass fraction of copper is 99.9-98 wt%;

step 2: putting materials required for smelting in a groove in a vacuum smelting furnace, and using a titanium ingot as a standard deoxidizing sample; then performing ventilation and deflation operationPumping the furnace body to 10^-1Low vacuum Pa, introducing high-purity argon, repeatedly washing with gas for more than 5 times to minimize oxygen concentration, and pumping to 10 deg.C^-4The method comprises the following steps of (1) exhausting oxygen in a smelting furnace in a high vacuum environment of Pa, and finally introducing argon to balance atmospheric pressure to ensure that the whole smelting process is in an argon protective environment;

and 5: pre-annealing the treated alloy in a tubular furnace filled with protective atmosphere gas, wherein the annealing temperature is 500-800 ℃; keeping the temperature in the annealing furnace for 240min-1440min, slowly cooling to 200 ℃ by program temperature control, cooling to room temperature along with the furnace, setting the program temperature control and cooling speed at 1 ℃/min, introducing protective atmosphere along with the whole heat treatment process with the furnace cooling speed of 5-8 ℃/min, and the gas flow rate of 50cm³/min。

Example 2:

step 1: mixing Si with the purity of 99.99 percent by mass fraction of 0.5 percent by weight and Se with the purity of 99.99 percent by mass fraction of 0.5 percent by weight with pure copper particles with the purity of 99.99 percent by mass fraction;

step 2: putting materials required for smelting in a groove in a vacuum smelting furnace, and using a titanium ingot as a standard deoxidizing sample; then, the gas is introduced and discharged, and the furnace body is pumped to 10^-1Low vacuum Pa, introducing high-purity argon, repeatedly washing with gas for more than 5 times to minimize oxygen concentration, and pumping to 10 deg.C^-4Making oxygen in the smelting furnace in a Pa high vacuum environmentExhausting gas, and finally introducing argon to balance atmospheric pressure to ensure that the whole smelting process is under the argon protection environment;

and step 3: before alloy smelting, the titanium ingot is repeatedly smelted, and oxygen is removed every time for more than 30 s. After smelting a titanium ingot, smelting the mixed material, and smelting each surface of each sample for 30s for 2-4 times to obtain an alloy product with uniform components and excellent performance;

and 4, step 4: and (3) polishing the alloy ingot obtained by smelting with abrasive paper, and then sequentially putting the alloy ingot into acetone and alcohol for ultrasonic cleaning to remove impurities. Then, putting the alloy into electrolyte for electrolytic polishing, ultrasonically cleaning the alloy after electrolytic polishing by using ethanol and deionized water, and finally drying the alloy by using a blower with cold air;

and 5: introducing pure H into the treated alloy₂Pre-annealing treatment in a gas tube furnace, wherein the annealing temperature is 700 ℃; keeping the temperature in the annealing furnace for 720min, slowly cooling to 200 ℃ by program temperature control, then cooling to room temperature along with the furnace, setting the program temperature control cooling speed to be 1 ℃/min, and introducing high-purity H in the whole heat treatment process₂Gas, gas flow rate is 50cm³/min。

Example 3:

step 1: mixing Si with the purity of 99.99 percent by mass fraction of 0.5 percent by weight and Te with the purity of 99.99 percent by mass fraction of 0.5 percent by weight with the mass fraction of 99 percent by weight with pure copper particles with the purity of 99.99 percent by mass fraction;

step 2: putting materials required for smelting in a groove in a vacuum smelting furnace, and using a titanium ingot as a standard deoxidizing sample; then, carrying out gas introducing and discharging operation, pumping the furnace body to 10-1Pa low vacuum, introducing high-purity argon, repeatedly carrying out gas washing operation for more than 5 times to ensure that the oxygen concentration reaches the lowest, pumping to a 10-4Pa high vacuum environment to exhaust oxygen in the smelting furnace, and finally introducing argon to balance the atmospheric pressure to ensure that the whole smelting process is an argon protective environment;

Example 4:

step 2: placing materials required by smelting in a groove in a vacuum smelting furnace, and using a titanium ingot as a standard deoxidizing sample; then, the gas is introduced and discharged, and the furnace body is pumped to 10^-1Low vacuum Pa, introducing high-purity argon, repeatedly washing with gas for more than 5 times to minimize oxygen concentration, and pumping to 10 deg.C^-4The method comprises the following steps of (1) exhausting oxygen in a smelting furnace in a high vacuum environment of Pa, and finally introducing argon to balance atmospheric pressure to ensure that the whole smelting process is in an argon protective environment;

and step 3: before the alloy is smelted, the titanium ingot is repeatedly smelted, and oxygen is removed for more than 30 seconds each time. After smelting a titanium ingot, smelting the mixed material, and smelting each surface of each sample for 30s for 2-4 times to obtain an alloy product with uniform components and excellent performance;

and 5: pre-annealing the treated alloy in a tube furnace filled with pure Ar gas, wherein the annealing temperature is 700 ℃; keeping the temperature in the annealing furnace for 720min, slowly cooling to 200 ℃ by program temperature control, then cooling to room temperature along with the furnace, setting the program temperature control cooling speed to be 1 ℃/min, introducing high-purity Ar gas in the whole heat treatment process, wherein the gas flow rate is 50cm³/min。

Example 5:

step 1: mixing Si with the purity of 99.99 percent by mass fraction of 1 percent by weight and Se with the purity of 99.99 percent by mass fraction of 1 percent by weight with pure copper particles with the purity of 99.99 percent by mass fraction of 99 percent by weight;

step 2: putting materials required for smelting in a groove in a vacuum smelting furnace, and using a titanium ingot as a standard deoxidizing sample; then, the gas is introduced and discharged, and the furnace body is pumped to 10^-1Low vacuum at Pa, introducing high-purity argon, repeatedly washing with gas for more than 5 times to minimize oxygen concentration, and pumping to 10^-4The method comprises the following steps of (1) exhausting oxygen in a smelting furnace in a high vacuum environment of Pa, and finally introducing argon to balance atmospheric pressure to ensure that the whole smelting process is in an argon protective environment;

and 5: pre-annealing the treated alloy in 2X 10 atmosphere²The annealing temperature of argon-hydrogen mixed gas of Pa hydrogen is 600 ℃; keeping the temperature in the annealing furnace for 1440min, directly cooling to room temperature along with the furnace after the pretreatment is finished, introducing protective argon-hydrogen atmosphere in the whole heat treatment process, wherein the gas flow rate is 50cm³/min。

Example 6:

step 1: mixing 1 wt% of Si with the purity of 99.99% and 0.5 wt% of Se with the purity of 99.99% with 99 wt% of pure copper particles with the purity of 99.99%;

and 5: introducing pure H into the treated alloy₂Pre-annealing treatment in a gas tube furnace at the annealing temperature of 600 ℃; keeping the temperature in the annealing furnace for 480min, directly cooling to room temperature along with the furnace after the pretreatment is finished, and introducing high-purity H in the whole heat treatment process₂Gas, gas flow rate is 50cm³/min。

Example 7:

step 1: mixing Si with the purity of 99.99 percent and Se with the mass fraction of 0.2 percent and the purity of 99.99 percent, wherein the mass fraction of the Si is 1 percent by weight, and the mass fraction of the Se is 99 percent by weight;

and 5: introducing pure H into the treated alloy₂Pre-annealing treatment in a gas tube furnace at 600 ℃; keeping the temperature in the annealing furnace for 720min, directly cooling to room temperature along with the furnace after the pretreatment is finished, and introducing high-purity H in the whole heat treatment process₂Gas, gas flow rate is 50cm³/min。

In the present invention, experimental analysis is performed on the above embodiments, and the following conclusions are reached:

referring to fig. 1, it is a thermogravimetric curve of the copper alloy obtained in examples 1-3 after annealing treatment, and the thermogravimetric test condition is the weight gain of oxidation at 400 ℃ for 2h under pure oxygen condition.

As shown in FIG. 1, the weight gains of the alloys obtained in example 1, example 2 and example 3 were 0.31107mg/cm²、0.27777mg/cm²、0.16796mg/cm². The weight gain of the alloy obtained in example 3 is only 5% of that of pure copper, so that compared with the pure copper sample under the same condition, the oxidation weight gain of the alloy sample designed by the invention is obviously reduced, and the relative oxidation resistance of Cu-Se-Si in the three alloy samples is slightly stronger.

Referring to fig. 2 and 3, XPS characterization, specifically surface element detection by a photoelectron spectrometer (XPS), was performed on the annealed Cu-Si-Se alloy in example 2 to obtain alloy surface element contents of Cu-3.59%, Si-33.85%, O-62.04%, and Se-0.52%. As can be seen, the surface of the alloy is mainly provided with Si and O signals, and as a result, FIG. 2 is an XPS analysis chart of an Si 2p orbit, the obtained peak value is 103.75eV, FIG. 3 is an XPS analysis chart of an O1s orbit, the obtained peak value is 532.9eV, and the corresponding binding energy and SiO are all corresponding to the peak value₂The bonding energy is consistent, so the surface of the alloy is considered to be SiO₂。

Referring to fig. 4, in order to further determine the composition of the alloy surface, XPS elemental etching analysis was performed on the annealed Cu — Si — Se alloy of example 6 for 0s, 25s, 100s, 200s, 400s, 700s, 1200s, 1800s, and 2400s, respectively; the elemental content per etch was obtained as shown. It can be seen that the alloy surface only contains Si element and O element before the etching for the first 400s, the content of Cu and Se is almost ignored, and as the etching time is increased, the Cu signal is increased, namely the content of Cu element is increased gradually, which indicates that a thicker SiO layer is formed on the alloy surface₂And (3) a membrane. When the etching time was 1200s, a Se signal peak began to appear, and the Se element content tended to increase.

Referring to FIG. 5, XPS characterization of the alloy at 1200s detected Se 3d peaks. I.e. in SiO₂The Se segregation layer exists under the oxide film, which shows that the alloy of the invention keeps the protection capability of the Se layer and further enhances the oxidation resistance of the copper alloy.

Referring to fig. 6 to 7, surface characterization SEM and element distribution maps of the Cu-Se-Si alloy samples obtained in examples 6 and 7 of the present invention show that the Cu-Se-Si alloy samples have flat surfaces after annealing, and Si and O signals are significant, and Cu and Se signals are relatively weak, corresponding to the XPS result.

FIG. 8 is a SEM image of the surface characterization of the Cu-Se-Si alloy sample obtained in example 6, and FIG. 9 is a SEM image of the surface characterization of the Cu-Se-Si alloy sample obtained in example 6 after being oxidized for 2h under 400 ℃ air condition. As shown in the figure, the alloy surface after 2h oxidation is relatively flat, no copper oxide whisker is generated, and compared with the alloy surface after annealing, no obvious change exists, which corresponds to the oxidation thermogravimetric curve weight gain result of the Cu-Se-Si alloy in figure 1.

Referring to FIG. 9, a cross-sectional representation SEM image and an element distribution diagram of the Cu-Se-Si alloy sample obtained in example 6, it can be seen that the element distribution near the surface can clearly show that the Si element and the O element are obviously aggregated on the surface of the alloy, and continuous and dense SiO is formed₂Oxide film, corresponding to XPS etching result. In addition, compared with the high temperature condition of more than 800 ℃ required by the copper-silicon alloy to form a compact oxide film, the alloy of the embodiment 6 of the invention can obtain compact SiO under the conditions of only 600 ℃ and 8 hours₂Layer, it can be seen that the addition of Se reduces SiO₂The forming temperature and time of the protective layer ensure a more complete protective structure of the alloy.

Referring to fig. 11, according to the application scenario of the copper material, an oxidation environment is simulated, and an oxidation experiment comparison test is performed on the alloy of the present invention at 400 ℃ in the atmosphere, as can be seen in the figure, a pure copper sample and an unannealed Cu-Se-Si sample are obviously blackened and oxidized, while the alloy sample after the pre-annealing treatment is oxidized at 400 ℃ for 24 hours without obvious change, and the surface is maintained bright, which proves that the oxidation resistance of the alloy of the present invention is significantly improved.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A preparation method of a novel high-temperature oxidation resistant multi-element copper alloy is characterized by comprising the following steps:

2. The preparation method of the novel high-temperature oxidation resistant multi-element copper alloy as claimed in claim 1, wherein in the step 1, raw materials Si and S (Se, Te) are both in small granular shape, the purity is 99.99%, powdery raw materials are avoided, and dust accumulation in the smelting process is prevented from influencing the alloy performance; avoid using blocky raw materials, prevent that the alloy from smelting unevenly.

3. The method for preparing the novel high-temperature oxidation resistant multi-element copper alloy as claimed in claim 1, wherein in the step 3, during the smelting process of the mixture, a smelting furnace is started for electromagnetic stirring, or the copper mixture is manually turned over through a metal spoon in the smelting furnace, and after each turning over, titanium ingots are remelted to remove oxygen escaped due to the movement of the metal spoon.

4. The method as claimed in claim 1, wherein in step 4, the copper alloy is sequentially mechanically polished and polished with 400-7000 mesh sand paper; the electrolyte is a mixed solution of phosphoric acid and ethanol, a mega-signal constant current source is adopted, the output current is 0.5-2A, the voltage is 3-5V, a copper alloy sample is placed into an anode, copper sheets are placed into the left side and the right side of the copper alloy sample as cathodes, a preset current is introduced, and the polishing time is 1-2 min.

5. The method as claimed in claim 1, wherein in step 5, the protective atmosphere is selected from the group consisting of high purity hydrogen, high purity argon, and a mixture thereof.