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Stress-field-training-based treatment method for improving magnetic-field-induced strain of polycrystalline NiMnGa alloy

A treatment method and stress field technology, applied in the field of effectively reducing the twinning stress of polycrystalline NiMnGa alloys and increasing the magnetically induced strain, can solve the problems of increased twinning stress, increased reorientation resistance of martensitic variants, and difficulty in obtaining magnetic Induced strain and other problems, to achieve the effect of improving magnetically induced strain and ensuring directionality

Active Publication Date: 2018-05-15
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the largest magnetically controlled shape memory effect of NiMnGa alloy is obtained in single crystal, which can reach 9.5%. However, the preparation process of single crystal is complicated and the preparation cost is high, which seriously limits the practical application of this kind of material.
In contrast, the preparation process of polycrystalline materials is relatively simple, and the cost is low, which is more advantageous in practical applications; however, due to the random distribution of martensite variants in polycrystalline materials, the twin stress will increase significantly, Leads to increased resistance to reorientation of martensitic variants driven by a magnetic field, making it difficult to obtain significant magnetically induced strain (magnetically controlled shape memory effect)

Method used

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  • Stress-field-training-based treatment method for improving magnetic-field-induced strain of polycrystalline NiMnGa alloy
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  • Stress-field-training-based treatment method for improving magnetic-field-induced strain of polycrystalline NiMnGa alloy

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Experimental program
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Effect test

Embodiment 1

[0038] Embodiment 1: Alloy composition Ni 50 mn 28 Ga 22 , sample size 3mm×4mm×5mm

[0039] (1) Alloy preparation

[0040] Using high-purity metal Ni (99.97wt.%), Mn (99.9wt.%), Ga (99.99wt.%) as raw materials, according to Ni 50 mn 28 Ga 22 (at.%) The nominal composition is weighed, and the polycrystalline parent alloy ingot is prepared by arc melting (repeated melting 4 times); subsequently, the parent alloy ingot is remelted and spray-cast into an alloy with a diameter of 10mm Rods; on this basis, the strongly oriented polycrystalline alloy rods were further prepared by directional solidification, and the drawing rate was 50 μm. In order to homogenize the composition of the alloy, the prepared directionally solidified alloy was packaged in a vacuum quartz tube for homogenization annealing, kept at 1173K for 24 hours and then water-cooled.

[0041] (2) Texture measurement and sample cutting

[0042] A disc with a thickness of 1 mm was cut from the directionally solid...

Embodiment 2

[0047] Embodiment 2: Alloy composition Ni 50 mn 28.5 Ga 21.5 , sample size 5mm×5mm×6mm

[0048] (1) Alloy preparation

[0049] Using high-purity metal Ni (99.97wt.%), Mn (99.9wt.%), Ga (99.99wt.%) as raw materials, according to Ni 50 mn 28.5 Ga 21.5 (at.%) The nominal composition is weighed, and the polycrystalline parent alloy ingot is prepared by arc melting (repeated melting 4 times); subsequently, the parent alloy ingot is remelted and spray-cast into an alloy with a diameter of 10mm Rods; On this basis, the directional solidification method is further used to prepare strongly oriented polycrystalline alloy rods, and the drawing rate is 100 μm. In order to homogenize the composition of the alloy, the prepared directionally solidified alloy was packaged in a vacuum quartz tube for homogenization annealing, kept at 1173K for 24 hours and then water-cooled.

[0050] (2) Texture measurement and sample cutting

[0051] A disc with a thickness of 1 mm was cut from the di...

Embodiment 3

[0056] Embodiment 3: alloy composition Ni 50 mn 29 Ga 21 , sample size 4mm×4mm×5mm

[0057] (1) Alloy preparation

[0058] Using high-purity metal Ni (99.97wt.%), Mn (99.9wt.%), Ga (99.99wt.%) as raw materials, according to Ni 50 mn 29 Ga 21(at.%) The nominal composition is weighed, and the polycrystalline parent alloy ingot is prepared by arc melting (repeated melting 4 times); subsequently, the parent alloy ingot is remelted and spray-cast into an alloy with a diameter of 10mm Rods; on this basis, the strongly oriented polycrystalline alloy rods were further prepared by directional solidification, and the drawing rate was 50 μm. In order to homogenize the composition of the alloy, the prepared directionally solidified alloy was packaged in a vacuum quartz tube for homogenization annealing, kept at 1173K for 24 hours and then water-cooled.

[0059] (2) Texture measurement and sample cutting

[0060] A disc with a thickness of 1 mm was cut from the directionally solidi...

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Abstract

The invention belongs to the technical field of new materials and provides a stress-field-training-based treatment method for improving magnetic-field-induced strain of polycrystalline NiMnGa alloy. According to the stress-field-training-based treatment method, Ni, Mn and Ga raw materials are smelted to cast a rod, the rod forms a high-orientation polycrystalline material after directional solidification, then the texture is measured through X-ray diffraction, a cuboid block sample is obtained through cutting according to crystal preferred orientation, and thus the three edges are all parallelto the direction of <001> preferred orientation of austenite. Repeated compression stress-field training is conducted on the cuboid sample through a mechanical property testing machine, compression is conducted alternately in two directions, with increase of the number of times of compression, the twin crystal stress platform of the sample is lowered significantly, and then the magnetic-field-induced strain of the polycrystalline alloy sample is improved.

Description

technical field [0001] The invention belongs to the technical field of new materials, and in particular relates to a processing method for effectively reducing the twinning stress of polycrystalline NiMnGa alloy and increasing the magnetically induced strain. Background technique [0002] NiMnGa ferromagnetic shape memory alloy is a new type of magnetic control functional material that has attracted widespread attention in recent years. This type of material will undergo a first-order martensitic transformation during the cooling process, from a high-temperature austenite phase to a low-temperature martensite phase. Due to the strong magnetocrystalline anisotropy of the martensite phase, the application of a magnetic field can induce the deformation and reorientation of the martensite to obtain significant magnetically induced strain, thus showing an excellent magnetic shape memory effect and output The advantages of large strain and high response frequency are ideal candid...

Claims

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Application Information

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IPC IPC(8): C22F1/10C22F3/00C22C19/03B22D27/04
CPCB22D27/045C22C19/03C22F1/10C22F3/00
Inventor 李宗宾李振庄杨波赵骧左良
Owner NORTHEASTERN UNIV