CN108929963B - A kind of preparation method of high wear resistance Ni50Mn34In16-xCox magnetic memory alloy - Google Patents

Abstract

The invention relates to a preparation method of a high wear resistance Ni ₅₀ Mn ₃₄ In _16-x Co _x magnetic memory alloy. A high wear-resistant Ni ₅₀ Mn ₃₄ In _16-x Co _x magnetic memory alloy is prepared as follows: 48-50 parts of Ni powder, 36-34 parts of Mn powder, 14-11 parts of In Powder and 2‑5Co powder, mixing, sintering, forming and heat treatment, to obtain Ni ₅₀ Mn ₃₄ In _16‑x Co _x alloy with high wear resistance. The wear resistance of Ni ₅₀ Mn ₃₄ In _16‑x Co _x alloy synthesized by powder forging method has been greatly improved, and the friction coefficient is 33‑50% lower than that of NiMnIn alloy.

Description

A kind of preparation method of high wear resistance Ni50Mn34In16-xCox magnetic memory alloy

technical field

The invention relates to a preparation method of high wear resistance Ni ₅₀ Mn ₃₄ In _16-x Co _x magnetic memory alloy.

Background technique

Smart materials are an important field of material research. At present, there are mainly piezoelectric materials, magnetostrictive materials and shape memory alloys. Piezoelectric ceramics represented by PZT and magnetostrictive materials represented by Terfenol-D can be used. It exhibits reversible strain under the action of an external electric/magnetic field, and the response frequency reaches 10KHz, but the maximum output strain is small (only about 0.2%) and the output stress is low (only a few MPa), while the traditional shape memory alloys represented by TiNi alloys Through thermomechanical training, it can have a two-way shape memory effect, with large output strain (4%) and high output force (tens of MPa), but limited by the temperature field, its response frequency is low (several Hz), which is difficult to meet the intelligent mechanism's high Urgent need for performance-driven materials.

Magnetic memory alloy can output macroscopic strain under the action of external magnetic field, and has both large strain and fast response, and is an ideal intelligent driving material. According to the mechanism of magnetically induced strain generation, magnetic shape memory alloys can be divided into two categories: one is represented by NiMnGa, whose magnetically induced strain originates from the rearrangement of martensite twinned variants driven by an external magnetic field, and the maximum magnetically induced strain can reach 10%, but the output stress is limited by the magnetocrystalline anisotropy, which is only a few MPa; the other type is represented by Ni-Mn-X (X=In, Sn, Sb) alloys whose magnetically induced strain source The mechanism of magneto-induced martensitic reverse transformation under the action of an external magnetic field is to deform the alloy in the martensitic state and place it in an ambient temperature slightly lower than the starting temperature of martensitic reverse transformation (A _s ). Applying a magnetic field to the alloy makes the _As temperature drop. When the _As temperature drops below the ambient temperature, the reverse martensitic transformation can occur without changing the ambient temperature, and the deformation can be recovered. Ni ₄₅ Co ₅ Mn _36.7 In _13.3 single crystal obtained 3% magnetron shape memory effect through magneto-induced martensitic reverse transformation, and the theoretical output stress can reach 108MPa. Unfortunately, the current magnetron shape memory effect obtained by NiCoMnIn alloy is one-way, which cannot meet the requirements of multiple reciprocating action mechanisms, and has poor wear resistance, which limits its practical application to a certain extent.

SUMMARY OF THE INVENTION

In order to solve the problem of poor wear resistance of existing Ni ₅₀ Mn ₃₄ In _16-x Co _x series magnetic memory alloys, the present invention provides a method for synthesizing Ni ₅₀ Mn ₃₄ In _16-x Co _x magnetic memory alloys by powder forging method.

The shape memory alloy of the present invention is prepared by the following method: using nickel powder, manganese powder, indium powder and cobalt powder with a purity of 99.95% and a powder diameter of 200 meshes as raw materials, taking 48-50 parts of Ni powder, 36-50 parts of Ni powder according to atomic percentage 34 parts of Mn powder, 14-11 parts of In powder, and 2-5Co powder were mixed uniformly by a mixer at 200 rpm-500 rpm, and then poured into the mold to press the preformed bar, and then Sinter at 500℃ for 1-2 hours, then put the sintered shaped blanks into a closed die forging machine for forging, and finally put the forged blanks into SXZ-10-12 box-type resistance furnace at temperature The homogenization heat treatment is carried out at 800-1200 ℃, and each element is diffused in a short distance to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In _16-x Co _x (x=2, 3, 4, 5) magnetic memory alloy is obtained.

Preferably, take 50 parts of Ni powder, 34 parts of Mn powder, 11 parts of In powder and 5Co powder according to atomic percentage, mix them uniformly with a stirrer under the condition of 300 rev/min, and pour the mixed powder into a mold to carry out The preformed bar is pressed, then sintered at 500 °C for 1 hour, and then the sintered shaped blank is put into a closed die forging machine for forging, and finally the forged blank is placed in a box-type resistance furnace at a temperature of Homogenization heat treatment is carried out at 1000°C, and each element is subjected to short-range diffusion to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In _16-5 Co ₅ magnetic memory alloy is obtained.

Grain refinement strengthening can significantly change the alloy's transformation temperature and improve its mechanical and physical properties. Therefore, for the first time, the method of synthesizing Ni ₅₀ Mn ₃₄ In _16-x Co _x magnetic memory alloy by powder forging is one of the effective methods to improve the mechanical properties of the alloy and improve the shape memory effect.

The beneficial effects of the present invention are:

1. The friction coefficient of the Ni ₅₀ Mn ₃₄ In _16-x Co _x (x=2, 3, 4, 5) alloy prepared by the present invention is 0.6-0.4, which is about 0.2-0.4 lower than the existing NiMnIn alloy;

2. The wear amount of the alloy prepared by the present invention is tested. As a result, the wear amount of the alloy prepared by the present invention becomes 0.0279g-0.0232g, which is about 0.002g lower than that of the existing NiMnInCo alloy;

3. The wear resistance of Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy synthesized by powder forging method has been greatly improved, and the friction coefficient is 33-50% lower than that of NiMnIn alloy.

4. The wear mechanism of the Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy prepared by the present invention is adhesive wear and abrasive wear, while the wear mechanism of the existing NiMnInCo alloy is abrasive wear.

Description of drawings

FIG. 1 is a test curve of the friction coefficient change of the high wear-resistance NiMnIn alloy prepared in Example 1 in the test of friction and wear.

Figure 2 shows the friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₄ Co ₂ alloy, and the change curve of friction coefficient.

Figure 3 shows the friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₃ Co ₃ alloy, and the change curve of friction coefficient.

Figure 4 shows the friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₂ Co ₄ alloy, and the change curve of friction coefficient.

Figure 5 shows the friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₁ Co ₅ alloy, and the change curve of friction coefficient.

Figure 6 shows the OM observation and analysis of the wear scar of Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy at room temperature. Among them, (a) is the friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₆ alloy, and the morphology of the wear scar; (b) is the friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₄ Co ₂ alloy, and the morphology of the wear scar; (c) Friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₃ Co ₃ alloy, and the morphology of wear scars; (d) Friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₂ Co ₄ alloy, and the morphology of wear scars; (e) The friction and wear test of Ni ₅₀ Mn ₃₄ In ₁₁ Co ₅ alloy, and the morphology of the wear scar.

Detailed ways

The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but does not limit the protection scope of the present invention. The press involved in the following examples is a YLJ-303 type micro press (JA2003N), and the box-type resistance furnace is an SXZ-10-12 box-type resistance furnace.

Example 1

Take 50 parts of Ni powder, 34 parts of Mn powder, and 16 parts of In powder according to atomic percentage, mix them uniformly with a stirrer at 300 rpm, pour the mixed powder into the mold to press the preformed bar, and then Sinter at 500°C for 1 hour, then put the sintered shaped blanks into a closed die forging machine for forging, and finally put the forged blanks into a box-type resistance furnace for uniformity at a temperature of 1000°C Chemical heat treatment, short-range diffusion of each element to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In ₁₆ magnetic memory alloy is obtained.

Example 2

Take 50 parts of Ni powder, 34 parts of Mn powder, 14 parts of In powder and 2 parts of Co powder according to atomic percentage, mix them uniformly with a mixer at 300 rpm, and pour the mixed powder into a mold for pressing The preformed bar is then sintered at 500 ° C for 1 hour, and then the sintered shaped blank is placed in a closed die forging machine for forging, and finally the forged blank is placed in a box-type resistance furnace at a temperature of 1000 The homogenization heat treatment is carried out under the condition of °C, and each element is diffused in a short range to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In ₁₄ Co ₂ magnetic memory alloy is obtained.

Example 3

Take 50 parts of Ni powder, 34 parts of Mn powder, 13 parts of In powder and 3 parts of Co powder according to atomic percentage, mix them uniformly with a mixer at 300 rpm, and pour the mixed powder into a mold for pressing The preformed bar is then sintered at 500°C for 1 hour, and then the sintered shaped blank is put into a closed die forging machine for forging, and finally the forged blank is placed in a box-type resistance furnace at a temperature of 1000 The homogenization heat treatment is carried out under the condition of °C, and each element is diffused in a short range to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In ₁₃ Co ₃ magnetic memory alloy is obtained.

Example 4

Take 50 parts of Ni powder, 34 parts of Mn powder, 12 parts of In powder and 4 parts of Co powder according to atomic percentage, mix them uniformly with a mixer at 300 rpm, and pour the mixed powder into a mold for pressing The preformed bar is then sintered at 500 ° C for 1 hour, and then the sintered shaped blank is placed in a closed die forging machine for forging, and finally the forged blank is placed in a box-type resistance furnace at a temperature of 1000 The homogenization heat treatment is carried out under the condition of °C, and each element is diffused in a short range to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In ₁₂ Co ₄ magnetic memory alloy is obtained.

Example 5

Take 50 parts of Ni powder, 34 parts of Mn powder, 11 parts of In powder and 5 parts of Co powder according to atomic percentage, mix them uniformly with a mixer at 300 rpm, and pour the mixed powder into a mold for pressing The preformed bar is then sintered at 500 ° C for 1 hour, and then the sintered shaped blank is placed in a closed die forging machine for forging, and finally the forged blank is placed in a box-type resistance furnace at a temperature of 1000 The homogenization heat treatment is carried out under the condition of °C, and each element is diffused in a short range to make it uniform. Finally, Ni ₅₀ Mn ₃₄ In ₁₁ Co ₅ magnetic memory alloy is obtained.

Table 1 is the result of the wear amount test performed on the alloy of Ni ₅₀ Mn ₃₄ In _16-x Co _x .

before wear g After wear/g Wear/g Ni₅₀Mn₃₄In₁₆ 6.8323 6.8044 0.0279 Ni₅₀Mn₃₄In_16-2Co₂ 6.9403 6.9141 0.0262 Ni₅₀Mn₃₄In_16-3Co₃ 6.2126 6.1871 0.0255 Ni₅₀Mn₃₄In_16-4Co₄ 5.9364 5.9126 0.0238 Ni₅₀Mn₃₄In_16-5Co₅ 5.9859 5.9627 0.0232

It can be seen from Table 1 that with the increase of Co element content, the friction coefficient of Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy gradually decreases. Combined with the observation of wear scars by OM, the principle of obtaining high wear resistance Ni ₅₀ Mn ₃₄ In _16-x Co _x alloys is revealed from the microscopic point of view. The friction coefficient of the Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy prepared by the method is reduced by about 33-50% compared with the NiMnIn alloy smelted in the melting furnace, and the wear amount is reduced by about 0.002 g.

The initial value of friction coefficient of Ni ₅₀ Mn ₃₄ In ₁₆ alloy is maintained at about 0.60, while that of Ni ₅₀ Mn ₃₄ In _16-2 Co ₂ alloy is maintained at about 0.55, and there is no significant difference between the two alloys. The large fluctuations may be related to the fact that the content of In-rich phase on the surface of the alloy is less, so that there are more strip martensite structures in the structure of the alloy surface. In Ni ₅₀ Mn ₃₄ In _16-3 Co ₃ alloy, the friction coefficient fluctuates slightly, but it is basically maintained around 0.5, but the fluctuation is not large. The change of the friction coefficient of Ni ₅₀ Mn ₃₄ In _16-4 Co ₄ alloy is similar to that of Ni ₅₀ Mn ₃₄ In _16-5 Co _5. The friction coefficient of the alloy is maintained at around 0.7 and fluctuates at the beginning. After 10 minutes of friction, the alloy's friction coefficient The coefficient of friction drops to around 0.45 and remains unchanged. The initial value of the friction coefficient of the Ni ₅₀ Mn ₃₄ In _16-5 Co ₅ alloy remained at about 0.60, and then there was an obvious drop, which fluctuated to about 0.40. After 2.5 minutes of friction, the friction coefficient of the alloy dropped to about 0.45. constant. This may be due to the existence of a large amount of -In-rich phase on the surface of the alloy during the friction process. According to a large number of data verified, the -In-rich phase is a soft phase, while martensite is a hard phase. During the process, when the friction pair contacts two phases with different hardness and hardness, the surface strength of the alloy is different, and the wear resistance is completely different.

Claims (3)

1. a preparation method of high wear resistance Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy ferromagnetic shape memory alloy, is characterized in that, comprises the following steps: S1. Take 50 parts of Ni powder, 34 parts of Mn powder, 14-11 parts of In powder and 2-5 parts of Co powder according to atomic percentage, and mix them uniformly by a stirrer; S2. Pour the metal powder evenly stirred in S1 into the mold to press the preformed rod; S3. Sinter the preformed rod of S2 at 500-600°C for 1-2 hours; S4. Put the sintered and formed blanks into a closed die forging machine for homogenization heat treatment at 800-1200° C. to make each element diffuse in a short range to make it uniform, to obtain a Ni ₅₀ Mn ₃₄ In _16-x Co _x Magnetic memory alloy, wherein x=2,3,4,5. 2 . The method for preparing a high wear-resistant Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy ferromagnetic shape memory alloy according to claim 1 , wherein in the step S1 raw materials are nickel powder, manganese powder, indium powder The purity of cobalt powder is 99.95%, and the diameter of the powder is 200 meshes. 3. the preparation method of a kind of high wear-resistance Ni ₅₀ Mn ₃₄ In _16-x Co _x alloy ferromagnetic shape memory alloy according to claim 1, is characterized in that, in described step S1, stirrer rotating speed is 200 rev// min-500 revolutions/min.

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