A heat treatment process for improving mechanical properties of tungsten-tantalum-nickel-titanium alloy

Abstract

The application discloses a heat treatment process for improving mechanical properties of a tungsten-tantalum-nickel-titanium alloy, and provides the heat treatment process which comprises the following steps: step S1, heating the tungsten-tantalum-nickel-titanium alloy to be treated to a solid solution temperature, keeping warm for a period of time, and oil cooling to room temperature; the solid solution temperature ranges from 850 DEG C to 1080 DEG C; step S2, heating the tungsten-tantalum-nickel-titanium alloy after the solid solution treatment to an aging temperature, keeping warm for a period of time, and cooling to room temperature. The application can effectively reduce or remove the Ni3Ti phase in the binder phase of the tungsten-tantalum-nickel-titanium alloy manufactured through vacuum sintering after cold isostatic pressing by high-temperature solid solution and low-temperature aging treatment, thereby improving the unevenness of the microstructure of the tungsten-tantalum-nickel-titanium alloy and improving the mechanical properties. The application has simple and controllable process, and the obtained product has excellent performance and is convenient for large-scale industrial application.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of tungsten alloy process treatment, and particularly relates to a heat treatment process for improving the mechanical properties of a tungsten-tantalum-nickel-titanium alloy. BACKGROUND

[0002] High specific gravity tungsten alloy is composed of tungsten phase and adhesive phase. Due to the unique combination of high density, mechanical strength, ductility, good machinability, corrosion resistance and economy, they are widely used in engine crankshaft balancer, shock absorber and damper of transmission system, rotating inertia element, precision machining tool, clock industry swing balance, optical precision instrument, lead substitute in sports equipment, etc.

[0003] The rapid development of science and technology puts forward higher requirements for the performance of high specific gravity tungsten alloy. The current research trend is to improve the microstructure of the alloy by preparing fine-grained, ultra-fine-grained or even nanocrystalline high specific gravity tungsten alloy, so as to obtain high-performance tungsten alloy. The strengthening technology of adding alloying elements or rare earth oxides is one of the important means to prepare high-performance high specific gravity tungsten alloy.

[0004] Tantalum, like tungsten, belongs to body-centered cubic (BCC) structure, can be infinitely solid-solved with tungsten, and the ordered phase formed in the tungsten-tantalum solid solution can improve the symmetry of the nuclear structure of tungsten and increase the mobility of dislocations, thereby improving the performance of tungsten particles. At the same time, the addition of tantalum can reduce the solubility of tungsten in the adhesive phase, thereby playing a fine-grained strengthening role. Compared with tungsten, the ductile-brittle transition temperature of tantalum is relatively low, which can effectively reduce the ductile-brittle transition temperature of tungsten alloy, and is an ideal strengthening element of tungsten. Near-equiatomic nickel and titanium form a NiTi (B2 structure) phase with the same crystal structure as tungsten, which has more advantages compared with the adhesive phase in the current tungsten alloy system (W-Ni-Fe, W-Ni-Cu). The phase transition characteristics of NiTi shape memory alloy are extremely sensitive to alloy composition, and a slight change in the proportion of the two elements will cause a large change in the phase transition temperature, thereby forming a brittle intermetallic compound. During the sintering process, Ni3Ti phase (rhombic structure) will also be generated, which greatly reduces the performance of the alloy. High-temperature solid solution can effectively reduce or remove the Ni3Ti phase, thereby improving the non-uniformity of the microstructure of the tungsten-tantalum-nickel-titanium alloy and improving its mechanical properties. SUMMARY

[0005] In view of the existing problems or improvement needs, the application provides a heat treatment process for improving the mechanical properties of a tungsten-tantalum-nickel-titanium alloy. The process comprises solid solution heating and aging heating, which aims to reduce or remove the Ni3Ti phase in the adhesive phase of the tungsten-tantalum-nickel-titanium alloy, thereby improving the non-uniformity of the microstructure of the tungsten-tantalum-nickel-titanium alloy and improving its mechanical properties.

[0006] According to the purpose of the present application, a heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy is provided, comprising the following steps:

[0007] (1) heating the tungsten-tantalum-nickel-titanium alloy to a solid solution temperature and maintaining for a period of time, and then oil cooling; the solid solution temperature ranges from 850 to 1080°C, preferably from 900 to 1050°C, and further preferably from 940 to 1010°C, and the maintaining time in the solid solution temperature range is 1 to 16 hours, preferably 2 to 5 hours, and further preferably 3 to 5 hours; in the tungsten-tantalum-nickel-titanium alloy, the mass ratio of W:Ta:(Ni+Ti) is (60 to 80):(10 to 30):(10 to 20), and preferably (70 to 80):(10 to 20):(10 to 20); and the mass ratio of nickel and titanium in the nickel-titanium alloy powder is (45 to 55):(45 to 55), and preferably (45 to 50):(50 to 55).

[0008] (2) heating the alloy obtained in step (1) to an aging temperature and maintaining for a period of time, and then oil cooling or air cooling; the aging temperature ranges from 350 to 650°C, preferably from 400 to 600°C, and further preferably from 490 to 560°C, which of course includes 500 to 555°C, 545 to 555°C, and the maintaining time in the aging temperature range is 1 to 16 hours, preferably 2 to 5 hours, and further preferably 3 to 5 hours.

[0009] Preferably, the tungsten-tantalum-nickel-titanium alloy is manufactured by vacuum sintering after cold isostatic pressing. The preparation process is known in the art; for example, tungsten powder, tantalum powder, and nickel-titanium alloy powder are taken according to the designed composition; after being mixed uniformly, cold isostatic pressing is performed; the cold isostatic pressing process is as follows: the cold isostatic pressing pressure is gradually increased to 250 MPa at a rate of 25 MPa / min, the pressure is maintained for 10 min, and then the pressure is decreased to 0 MPa at a rate of 10 MPa / min; after forming, vacuum sintering is performed; the vacuum sintering process is as follows: the temperature is increased to 900°C at a rate of 10°C / min, the temperature is maintained for 60 min, then the temperature is increased to 1350°C at a rate of 5°C / min, and finally the temperature is decreased to room temperature at a rate of 5°C / min.

[0010] Preferably, the tungsten-tantalum-nickel-titanium alloy uses elemental powder for tungsten powder and tantalum powder, and alloy powder for nickel-titanium powder.

[0011] Preferably, the tungsten-tantalum-nickel-titanium alloy has a mass fraction ratio of tungsten powder: tantalum powder: nickel-titanium alloy powder of (60 to 80):(10 to 30):(10 to 20), and preferably (70 to 80):(10 to 20):(10 to 20); and the mass ratio of nickel and titanium in the nickel-titanium alloy powder is (45 to 55):(45 to 55), and preferably (45 to 50):(50 to 55).

[0012] Preferably, the selected heat treatment process in combination with the selected composition can effectively reduce or eliminate the Ni3Ti phase in the binder phase, thereby improving the non-uniformity of the microstructure of the tungsten-tantalum-nickel-titanium alloy and improving the tensile strength thereof.

[0013] Preferably, the tungsten-tantalum-nickel-titanium alloy obtained after the heat treatment is free of the Ni3Ti phase. As a further preference, the tungsten-tantalum-nickel-titanium alloy obtained after the heat treatment contains the NiTi phase (B19' structure). As a still further preference, the tungsten-tantalum-nickel-titanium alloy obtained after the heat treatment contains the NiTi phase (B19' structure) and the Ni4Ti3 phase.

[0014] The present application, through the synergistic effect of the composition and the heat treatment process parameters, obtains a high-strength tungsten-tantalum-nickel-titanium alloy with a tensile strength of 960-1109 MPa and a total elongation of 6.4%-9.25%. After optimization, the high-strength tungsten-tantalum-nickel-titanium alloy has a tensile strength of 1050-1109 MPa and a total elongation of 8.2%-9.25%. After further optimization, the high-strength tungsten-tantalum-nickel-titanium alloy has a tensile strength of 1100-1109 MPa and a total elongation of 8.5%-9.25%.

[0015] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0016] (1) The present application heats the tungsten-tantalum-nickel-titanium alloy manufactured by vacuum sintering after cold isostatic pressing to the solid solution temperature in vacuum or a protective atmosphere, reduces or eliminates the Ni3Ti phase in the binder phase through solid solution heat treatment, thereby improving the non-uniformity of the microstructure of the tungsten-tantalum-nickel-titanium alloy; and heats the tungsten-tantalum-nickel-titanium alloy after the solid solution treatment to the aging temperature in vacuum or a protective atmosphere, further regulates the composition of the binder phase through aging heat treatment, and improves the material performance.

[0017] (2) The tungsten-tantalum-nickel-titanium alloy after the solid solution and aging heat treatment in the present application has higher tensile strength and total elongation than the alloy without heat treatment. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The tensile curve of the tungsten-tantalum-nickel-titanium alloy provided for the comparative examples 1-3 and the working examples 1-5 of the present application is shown in the following figure.

[0019] Figure 2 The microstructure, energy spectrum point scanning results, and XRD pattern of the tungsten-tantalum-nickel-titanium alloy not subjected to heat treatment and manufactured by vacuum sintering after cold isostatic pressing provided for the comparative example 1 of the present application are shown in the following figure.

[0020] Figure 3 The microstructure, energy spectrum point scanning results, and XRD pattern of the tungsten-tantalum-nickel-titanium alloy subjected to solid solution and aging treatment provided for the comparative example 2 of the present application are shown in the following figure.

[0021] Figure 4 The microstructure, energy spectrum point scanning result and XRD pattern of the solution and aging treated tungsten-tantalum-nickel-titanium alloy provided for the present application comparative example 3.

[0022] Figure 5 The microstructure, energy spectrum point scanning result and XRD pattern of the solution and aging treated tungsten-tantalum-nickel-titanium alloy provided for the present application comparative example 3.

[0023] Figure 6 The microstructure, energy spectrum point scanning result and XRD pattern of the solution and aging treated tungsten-tantalum-nickel-titanium alloy provided for the present application comparative example 3.

[0024] Figure 7 The microstructure, energy spectrum point scanning result and XRD pattern of the solution and aging treated tungsten-tantalum-nickel-titanium alloy provided for the present application comparative example 3.

[0025] Figure 8 The microstructure, energy spectrum point scanning result and XRD pattern of the solution and aging treated tungsten-tantalum-nickel-titanium alloy provided for the present application comparative example 3.

[0026] Figure 9 The microstructure, energy spectrum point scanning result and XRD pattern of the solution and aging treated tungsten-tantalum-nickel-titanium alloy provided for the present application comparative example 3.

[0027] Figure 10 The solution and aging treated tungsten-tantalum-nickel-titanium alloy heat treatment process flow chart of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0029] The present application is a heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy, Figure 10 The present application is a tungsten-tantalum-nickel-titanium alloy heat treatment process flow chart, comprising the following steps:

[0030] S1: heat the tungsten-tantalum-nickel-titanium alloy to a solution temperature and keep it for a period of time, and then oil cooling; the solution temperature range is 850-1050℃, and the holding time in the solution temperature range is 1-16h.

[0031] S2: heat the alloy obtained in step S1 to an aging temperature and keep it, and then oil cooling or air cooling; the range is 350-650℃, and the holding time in the aging temperature range is 1-16h.

[0032] In some embodiments, the tungsten-tantalum-nickel-titanium alloy is manufactured by vacuum sintering after cold isostatic pressing.

[0033] In some embodiments, the tungsten-tantalum-nickel-titanium alloy uses elemental tungsten powder and elemental tantalum powder as the raw material, and uses nickel-titanium alloy powder as the raw material.

[0034] In some embodiments, the mass ratio of the tungsten powder, the tantalum powder and the nickel-titanium alloy powder in the high-strength tungsten-tantalum-nickel-titanium alloy is (60-80):(10-30):(10-20), and the mass ratio of nickel and titanium in the nickel-titanium alloy powder is (45-55):(45-55).

[0035] In some embodiments, the heat treatment process cooperates with the selected composition to effectively reduce or remove the Ni3Ti phase in the binder phase, thereby improving the non-uniformity of the microstructure of the high-strength tungsten-tantalum-nickel-titanium alloy and improving the tensile strength.

[0036] The following are specific comparative examples and examples

[0037] Comparative Example 1

[0038] A tungsten-tantalum-nickel-titanium alloy manufactured by vacuum sintering after cold isostatic pressing without heat treatment. The mass ratio of the tungsten powder, the tantalum powder and the nickel-titanium alloy powder in the alloy is 80:10:10, and the mass ratio of nickel and titanium in the nickel-titanium alloy powder is 55:45. The cold isostatic pressing process is: gradually increasing the cold isostatic pressing pressure to 250 MPa at a rate of 25 MPa / min, maintaining the pressure for 10 min, and then reducing the pressure to 0 MPa at a rate of 10 MPa / min. The vacuum sintering process is: increasing the temperature to 900℃ at a rate of 10℃ / min, maintaining the temperature for 60 min, then increasing the temperature to 1350℃ at a rate of 5℃ / min, and finally decreasing the temperature to room temperature at a rate of 5℃ / min. Figure 1 The tensile curve of the high-strength tungsten-tantalum-nickel-titanium alloy manufactured by vacuum sintering after cold isostatic pressing without heat treatment provided in Comparative Example 1 of the present application.

[0039] Figure 2 The microstructure, energy spectrum point scanning results and XRD pattern of the high-strength tungsten-tantalum-nickel-titanium alloy manufactured by vacuum sintering after cold isostatic pressing without heat treatment provided in Comparative Example 1 of the present application. From the figure, Figure 2 It can be seen that the white particles are tungsten particles, and the gray particles are binder phases; the binder phases of the high-strength tungsten-tantalum-nickel-titanium alloy without heat treatment are composed of NiTi phase (B19' structure), Ti2Ni phase and Ni3Ti phase.

[0040] Comparative Example 2

[0041] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0042] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on the vacuum pump to maintain a vacuum state. The composition, molding process parameters, and vacuum sintering process parameters of the alloy are the same as those of Comparative Example 1;

[0043] (2) Solution heat treatment: heating to 1150°C at a heating rate of 10°C / min, keeping at this temperature for 4 h, and oil cooling to room temperature;

[0044] (3) Aging heat treatment: heat to 550℃ at a heating rate of 10℃ / min, keep warm for 4h, and oil cool to room temperature.

[0045] Depend on Figure 1 It can be seen that when the high-temperature solution heat treatment temperature reaches 1150°C, which exceeds the protection range of the present invention, the tensile properties drop sharply, the tensile strength is only 484.2 MPa, and the total elongation is only 4.22%.

[0046] Figure 3 The microstructure, energy spectrum scanning results and XRD pattern of the solution-aged tungsten-tantalum-nickel-titanium alloy provided in Comparative Example 2 of the present invention are as follows. Figure 3 It can be seen that the bonding phase of the tungsten-tantalum-nickel-titanium alloy after heat treatment is composed of Ti2Ni phase and Ni3Ti phase. A large amount of Ni3Ti phase is not processed, which has an adverse effect on the tensile strength of the alloy and causes the tensile strength to drop sharply.

[0047] Comparative Example 3

[0048] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0049] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on a vacuum pump to maintain a vacuum state; the mass fraction ratio of the alloy tungsten powder, tantalum powder and nickel-titanium alloy powder is 80:10:10, and the mass ratio of nickel to titanium in the nickel-titanium alloy powder is 70:30; the molding process parameters and vacuum sintering process parameters are the same as those of Comparative Example 1;

[0050] (2) Solution heat treatment: heating to 1000°C at a heating rate of 10°C / min, keeping at this temperature for 4 h, and oil cooling to room temperature;

[0051] (3) Aging heat treatment: heat to 550℃ at a heating rate of 10℃ / min, keep warm for 4h, and oil cool to room temperature.

[0052] Depend on Figure 1It can be seen that when the mass ratio of nickel to titanium in the nickel-titanium alloy powder in the alloy is 70:30, which is not within the scope of protection of the present invention, the tensile properties drop sharply, the tensile strength is only 422.80 MPa, and the total elongation is only 5.06%.

[0053] Figure 4 The microstructure, energy spectrum scanning results and XRD pattern of the solution-aged tungsten-tantalum-nickel-titanium alloy provided in Comparative Example 3 of the present invention are as follows. Figure 4 It can be seen that when the mass ratio of nickel to titanium in the tungsten-tantalum-nickel-titanium alloy (70:30) is not within the protection scope of the present invention, the bonding phase of the tungsten-tantalum-nickel-titanium alloy after heat treatment is composed of Ni3Ti.

[0054] Example 1

[0055] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0056] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on the vacuum pump to maintain a vacuum state. The composition, molding process parameters, and vacuum sintering process parameters of the alloy are the same as those of Comparative Example 1;

[0057] (2) Solution heat treatment: heating to 850°C at a rate of 10°C / min, keeping at this temperature for 2 h, and oil cooling to room temperature;

[0058] (3) Aging heat treatment: heat to 400℃ at a heating rate of 10℃ / min, keep warm for 2h, and oil cool to room temperature.

[0059] Depend on Figure 1 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the ultimate tensile strength of the treated tungsten-tantalum-nickel-titanium alloy is increased from 773.48 MPa to 960.40 MPa, and the total elongation is increased from 2.50% to 6.40%.

[0060] Figure 5 The microstructure, energy spectrum scanning results and XRD pattern of the solution-aged tungsten-tantalum-nickel-titanium alloy provided in Example 1 of the present invention. Figure 5 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the Ni3Ti phase in the bonding phase is removed and the Ni4Ti3 phase is precipitated; the bonding phase is composed of NiTi phase (B19' structure), Ni4Ti3 phase and Ti2Ni phase.

[0061] Example 2

[0062] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0063] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on the vacuum pump to maintain a vacuum state. The composition, molding process parameters, and vacuum sintering process parameters of the alloy are the same as those of Comparative Example 1;

[0064] (2) Solution heat treatment: heating to 850°C at a heating rate of 10°C / min, keeping at this temperature for 4 h, and oil cooling to room temperature;

[0065] (3) Aging heat treatment: heat to 400℃ at a heating rate of 10℃ / min, keep warm for 2h, and oil cool to room temperature.

[0066] Depend on Figure 1 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the ultimate tensile strength of the treated tungsten-tantalum-nickel-titanium alloy is increased from 773.48 MPa to 1013.85 MPa, and the total elongation is increased from 2.50% to 7.18%.

[0067] Figure 6 The microstructure, energy spectrum scanning results and XRD pattern of the solution-aged tungsten-tantalum-nickel-titanium alloy provided in Example 2 of the present invention. Figure 6 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the Ni3Ti phase in the bonding phase is removed and the Ni4Ti3 phase is precipitated; the bonding phase is composed of NiTi phase (B19' structure), Ni4Ti3 phase and Ti2Ni phase.

[0068] Example 3

[0069] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0070] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on the vacuum pump to maintain a vacuum state. The composition, molding process parameters, and vacuum sintering process parameters of the alloy are the same as those of Comparative Example 1;

[0071] (2) Solution heat treatment: heating to 900°C at a heating rate of 10°C / min, keeping at this temperature for 4 h, and oil cooling to room temperature;

[0072] (3) Aging heat treatment: heat to 500℃ at a heating rate of 10℃ / min, keep warm for 2h, and oil cool to room temperature.

[0073] Depend on Figure 1 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the ultimate tensile strength of the treated tungsten-tantalum-nickel-titanium alloy is increased from 773.48 MPa to 1057.94 MPa, and the total elongation is increased from 2.50% to 8.30%.

[0074] Figure 7 The microstructure, energy spectrum scanning results and XRD pattern of the solution-aged tungsten-tantalum-nickel-titanium alloy provided in Example 3 of the present invention.Figure 7 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the Ni3Ti phase in the bonding phase is removed, and the bonding phase only consists of the NiTi phase (B19' structure).

[0075] Example 4

[0076] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0077] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on the vacuum pump to maintain a vacuum state. The composition, molding process parameters, and vacuum sintering process parameters of the alloy are the same as those of Comparative Example 1;

[0078] (2) Solution heat treatment: heating to 950°C at a heating rate of 10°C / min, keeping at this temperature for 4 h, and oil cooling to room temperature;

[0079] (3) Aging heat treatment: heat to 500℃ at a heating rate of 10℃ / min, keep warm for 4h, and oil cool to room temperature.

[0080] Depend on Figure 1 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the ultimate tensile strength of the treated tungsten-tantalum-nickel-titanium alloy is increased from 773.48 MPa to 1107.28 MPa, and the total elongation is increased from 2.50% to 8.53%.

[0081] Figure 8 The microstructure, energy spectrum scanning results and XRD pattern of the solution-aged tungsten-tantalum-nickel-titanium alloy provided in Example 4 of the present invention. Figure 8 It can be seen that compared with the untreated tungsten-tantalum-nickel-titanium alloy, the Ni3Ti phase in the bonding phase is removed, and the bonding phase is composed of NiTi phase (B19' structure) and Ni4Ti3 phase.

[0082] Example 5

[0083] A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy comprises the following steps:

[0084] (1) placing the tungsten-tantalum-nickel-titanium alloy to be processed in a vacuum tube furnace, and turning on the vacuum pump to maintain a vacuum state. The composition, molding process parameters, and vacuum sintering process parameters of the alloy are the same as those of Comparative Example 1;

[0085] (2) Solution heat treatment: heating to 1000°C at a heating rate of 10°C / min, keeping at this temperature for 4 h, and oil cooling to room temperature;

[0086] (3) Aging heat treatment: heat to 550℃ at a heating rate of 10℃ / min, keep warm for 4h, and oil cool to room temperature.

[0087] Depend on Figure 1It can be seen that, compared with the untreated tungsten-tantalum-nickel titanium alloy, the ultimate tensile strength of the treated tungsten-tantalum-nickel titanium alloy is increased from 773.48 MPa to 1108.42 MPa, and the total elongation is increased from 2.50% to 9.18%.

[0088] Figure 9 The microstructure, energy spectrum point scanning results and XRD patterns of the solution and aging treated tungsten-tantalum-nickel titanium alloy provided for the embodiment 5 of the present application are shown in the following table. Figure 9 It can be seen that, compared with the untreated tungsten-tantalum-nickel titanium alloy, the Ni3Ti phase in the binder phase is removed, and the binder phase is composed of NiTi phase (B19' structure) and Ni4Ti3 phase.

[0089] The mechanical properties of the tungsten-tantalum-nickel titanium alloy material after heat treatment in the present application are shown in the following table:

[0090]

[0091]

[0092] From the data of the above table, it can be seen that the tensile properties of the alloys not within the protection scope of the present application are poor; and the data of the embodiments 1-5 show that, within the protection scope of the present application, the tensile strength and total elongation of the solution and aging treated tungsten-tantalum-nickel titanium alloy are greatly improved.

[0093] It is easy for those skilled in the art to understand that the above description is only the preferred embodiments of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy, characterized in that: The steps include: (1) heating a tungsten-tantalum-nickel-titanium alloy to a solution temperature and holding the temperature for a period of time, and then oil cooling; the solution temperature range is 850-1080°C, and the holding time within the solution temperature range is 1-16 hours; in the tungsten-tantalum-nickel-titanium alloy, the mass ratio of W:Ta:(Ni+Ti)=(60-80):(10-30):(10-20), and the mass ratio of nickel to titanium is (45-55):(45-55); (2) The alloy obtained in step (1) is heated to an aging temperature and kept at the temperature, and then oil-cooled or air-cooled; the aging temperature range is 350-650°C, and the holding time within the aging temperature range is 1-16 h; the tungsten-tantalum-nickel-titanium alloy obtained after heat treatment has no Ni3Ti phase.

2. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 1, characterized in that: In step (1), in the tungsten-tantalum-nickel-titanium alloy, the mass ratio of W:Ta:(Ni+Ti)=(70-80):(10-20):(10-20); the mass ratio of nickel to titanium in the nickel-titanium alloy powder is (45-50):(50-55).

3. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 1, characterized in that: In step (1), the solution temperature is 900-1050°C and the solution time is 2-5h.

4. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 3, characterized in that: The solution temperature is 940~1010℃ and the solution time is 3-5h.

5. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 1, characterized in that: In step (2), the aging temperature is 400-600°C, and the aging time is 2-5h.

6. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 1, characterized in that: In step (2), the aging temperature is 490-560°C, and the aging time is 3-5h.

7. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 6, characterized in that: The tungsten-tantalum-nickel-titanium alloy obtained after heat treatment contains NiTi phase.

8. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 6, characterized in that: The tungsten-tantalum-nickel-titanium alloy obtained after heat treatment contains NiTi phase and Ni4Ti3 phase.

9. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 1, characterized in that: The obtained high-strength tungsten-tantalum-nickel-titanium alloy has a tensile strength of 960~1109MPa and a total elongation of 6.4%~9.25%.

10. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 9, characterized in that: The obtained high-strength tungsten-tantalum-nickel-titanium alloy has a tensile strength of 1050~1109MPa and a total elongation of 8.2%~9.25%.

11. The heat treatment process for improving the mechanical properties of tungsten-tantalum-nickel-titanium alloy according to claim 10, characterized in that: The obtained high-strength tungsten-tantalum-nickel-titanium alloy has a tensile strength of 1100~1109MPa and a total elongation of 8.5%~9.25%.

Images