CN102912271B - Second-phase electrical stimulation nodulizing method for Ni-enriched TiNi shape memory alloy - Google Patents

Abstract

The invention provides a second-phase electrical stimulation nodulizing method for Ni-enriched TiNi shape memory alloy. The method comprises steps as follows: driving the TiNi memory alloy belt or plate to move at a certain speed by a roller through electric plasticity roller; inputting high-energy pulse current output by a pulse power supply to an electrifying part of the moving TiNi alloy through an electrode; and carrying out joule heating effect and electron wind non-thermal effect on the electrifying part, so as to transform the internal microscopic structure from the initial sheet sor polygonal second phase to uniformly distributed spherical second phase while being subjected to solution treatment. The processed TiNi alloy belt or the plate can be cooled by air at room temperature. According to the method, the implementation time is short, the production efficiency is high, and the TiNi alloy is prevented from oxidizing at high temperature.

Description

Rich Ni state TiNi shape memory alloy second-phase electricity irritation spheronization process

Technical field

The present invention is a kind of rich Ni state TiNi shape memory alloy second-phase electricity irritation spheronization process, belongs to the extraordinary heat treatment technics of metal field.

Background technology

Shape memory alloy has the dual-use function of sensing and driving concurrently, that to realize physical construction microminiaturized and intelligentizedly have most a selection, especially, TiNi base marmem has abundant phase transition phenomena, excellent shape memory and superelastic properties, good mechanical property, erosion resistance and high damping characteristic, has the application prospect as solid-state drive most.In rich Ni state (>=50.6at.%) TiNi alloy, Ti ₃ni ₄in the martensitic transformation feature of phase behaviour (volume fraction, pattern and distribution) alloy, the changes in distribution of R transformation and matrix Ni content thereof plays crucial impact.By Ti that prior heat treatment obtains ₃ni ₄the appearance that the existence of phase has caused multistage martensitic phase to change, thus alloy phase change restorer and recoverable strain value reduced.How to pass through to adjust Ti ₃ni ₄phase behaviour, controls Ti ₃ni ₄the Ni content distribution gradient of phase/TiNi phase basal body interface, reduces the number of stages that martensitic phase changes, and improves phase transformation restorer, is one of key factor of restriction TiNi alloy engineering application.

Summary of the invention

The deficiency that the present invention exists for prior art just and design a kind of rich Ni state TiNi shape memory alloy second-phase electricity irritation spheronization process is provided, its objective is to make rich Ni state TiNi shape memory alloy second-phase that complete nodularization occur, and has reduced Ti ₃ni ₄the Ni content distribution gradient of phase/TiNi phase basal body interface, only occurs that two rank martensitic phases change, and can farthest improve phase transformation restorer.

The object of the invention is to be achieved through the following technical solutions:

This kind of rich Ni state TiNi shape memory alloy second-phase electricity irritation spheronization process, is characterized in that: the step of the method is:

(1) the atomic percent of the Ni content in described rich Ni state TiNi shape memory alloy is more than or equal to 50.8%;

(2) the band of TiNi shape memory alloy or sheet material (3) are realized to the way moving of band or sheet material (3) by decoiling equipment (5), wrap-up (6), roll (2) and two groups of supporting rolls (1) of milling train, between band or sheet material (3) and roll (2) and two groups of supporting rolls (1), it is Elastic Contact, the translational speed of band or sheet material (3) is 0.3～3m/min, band or sheet material (3) width be 5～300mm, thickness is 0.5～5mm;

(3) between one group of supporting roll (1) and roll (2), connect high energy pulse power supply (4), the band or the sheet material (3) that between this group supporting roll (1) and roll (2), power up part are carried out to second-phase electricity irritation spheroidizing, powering up partial-length L is 50～200mm, the discharge parameter of high energy pulse power supply (4) is: discharge frequency 1500～3000Hz, pulse width 20～3000 μ s, are carried in the amplitude 800～3000A/mm of the current density on band or sheet material (3) ².

Technical solution of the present invention utilizes existing rolling mill structure to drive the band of TiNi shape memory alloy or sheet material (3) to press the speed way moving of setting, in moving process, tight Elastic Contact between band or sheet material (3) and supporting roll (1) and roll (2), its rotation drives by direct-current machine, the electric current of high energy pulse power supply (4) produces joule heating effect and electron wind non-thermal effect to powering up part, make the temperature of band or sheet material (3) can reach 650～900 DEG C, like this, the internal microstructure of band or sheet material (3) is transformed into by sheet or the polygon-shaped second-phase of initial state the spherical second-phase being evenly distributed, or make second-phase solid solution in matrix.By above-mentioned TiNi alloy strip steel rolled stock after treatment or sheet material air cooling at ambient temperature.

The advantage of technical solution of the present invention is:

1, in TiNi shape memory alloy electricity irritation spheroidizing process, high energy pulse electric current was directly inputted to and in alloy, produced important joule heating effect and electron wind non-thermal effect moment, under the coupling of these two kinds of effects, the vibrational energy of atom is sharply increased, promoted the diffusion of the inner atom of alloy.Rich Ni state TiNi alloy inside through prior heat treatment presents sheet or irregular shape particle, at second-phase tip or rejected region, the selective effect of electricimpulse further promotes the diffusion of Ni atom, has realized solid solution and the nodularization of sheet and particle shape second-phase.

2, the rich Ni state TiNi shape memory alloy that adopts prior heat treatment process processing, alloy second-phase is separated out with sheet or random particulate state, in process of cooling, multistage martensitic phase occurs and changes; After electricity irritation is processed, solid solution and the nodularization of sheet and particle shape second-phase in TiNi alloy, in process of cooling, martensitic phase becomes two rank.

3, in electricity irritation treating processes, on rich Ni state TiNi shape memory alloy band or sheet material when the complete spheroidizing in any point in 22s, processing top temperature is 1050 DEG C, and prior heat treatment mode cannot obtain second-phase spherodized structure, heat up fast and lower the temperature and can avoid TiNi alloy that oxidative phenomena does not occur

Brief description of the drawings

Fig. 1 is the schematic diagram of technical solution of the present invention to TiNi alloy strip steel rolled stock or sheet material electricity irritation nodulizing process

Fig. 2 is the microstructure of the rich Ni state TiNi shape memory alloy after 800 DEG C of traditional timeliness thermal treatments

Fig. 3 is the microstructure that adopts the technology of the present invention electricity irritation rich Ni state TiNi shape memory alloy after treatment

Embodiment

Below with reference to drawings and Examples, technical solution of the present invention is further described:

Shown in accompanying drawing 1, this kind of rich Ni state TiNi shape memory alloy second-phase electricity irritation spheronization process, is characterized in that: the step of the method is:

(1) the atomic percent of the Ni content in described rich Ni state TiNi shape memory alloy is more than or equal to 50.8%;

(2) by the band of TiNi shape memory alloy or sheet material 3, the decoiling equipment 5 by milling train, wrap-up 6, roll 2 and two groups of supporting rolls 1 are realized the way moving of band or sheet material 3, between band or sheet material 3 and roll 2 and two groups of supporting rolls 1, it is Elastic Contact, it between roll 2 and TiNi alloy strip steel rolled stock or sheet material 3, must be Elastic Contact closely, there is not viscous deformation in alloy strip steel rolled stock or sheet material 3, the translational speed of band or sheet material 3 is 0.3～3m/min, band or sheet material 3 width be 5～300mm, thickness is 0.5～5mm;

(3) between one group of supporting roll 1 and roll 2, connect high energy pulse power supply 4, between high energy pulse power supply 4 and supporting roll 1 and roll 2, realize and electrically contacting by brush, the band or the sheet material 3 that between this group supporting roll 1 and roll 2, power up part are carried out to second-phase electricity irritation spheroidizing, powering up partial-length L is 50～200mm, the discharge parameter of high energy pulse power supply 4 is: discharge frequency 1500～3000Hz, pulse width 20～3000 μ s, are carried in the amplitude 800～3000A/mm of the current density on band or sheet material 3 ², make the temperature of band or sheet material 3 can reach 650～900 DEG C, electricity irritation spheroidizing process is in room temperature and air, without adopting heat-eliminating medium to carry out cooling to band after treatment or sheet material 3.

Fig. 3 is the microstructure that adopts the technology of the present invention electricity irritation rich Ni state TiNi shape memory alloy after treatment, and the discharge parameter of electricity irritation processing is: frequency 1500Hz, electronic pulse width 60 μ s, current density 800A/mm ².The processing treatment temp of band or sheet material 3 can reach 800 DEG C.By the contrast of Fig. 3 and Fig. 2, in the rear TiNi alloy of electricity irritation processing there is complete nodularization in sheet and particle shape second-phase.

Compared with prior art, the inventive method makes rich Ni state TiNi shape memory alloy second-phase that complete nodularization occur, and has reduced Ti ₃ni ₄the Ni content distribution gradient of phase/TiNi phase basal body interface, only occurs that two rank martensitic phases change, and can farthest improve phase transformation restorer.This treatment process time is short, and production efficiency is high, has avoided the high temperature oxidation of TiNi alloy simultaneously.

Claims (1)

1. a rich Ni state TiNi shape memory alloy second-phase electricity irritation spheronization process, is characterized in that: the step of the method is:

(1) the atomic percent of the Ni content in described rich Ni state TiNi shape memory alloy is more than or equal to 50.8%;

(2) the band of TiNi shape memory alloy or sheet material (3) are realized to the way moving of band or sheet material (3) by decoiling equipment (5), wrap-up (6), roll (2) and two groups of supporting rolls (1) of milling train, between band or sheet material (3) and roll (2) and two groups of supporting rolls (1), it is Elastic Contact, the translational speed of band or sheet material (3) is 0.3～3m/min, the width of band or sheet material (3) is 5～300mm, and thickness is 0.5～5mm;

(3) between one group of supporting roll (1) and roll (2), connect high energy pulse power supply (4), the band or the sheet material (3) that between this group supporting roll (1) and roll (2), power up part are carried out to second-phase electricity irritation spheroidizing, powering up partial-length L is 50～200mm, the discharge parameter of high energy pulse power supply (4) is: discharge frequency 1500～3000Hz, pulse width 20～3000 μ s, are carried in the amplitude 800～3000A/mm of the current density on band or sheet material (3) ².