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A treatment method for improving magnetically induced strain in polycrystalline nimnga alloys based on stress field training

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 problem of increased twinning stress, increased reorientation resistance of martensitic variants, and limited practical applications and other issues to achieve the effect of ensuring directionality and improving magnetically induced strain

Active Publication Date: 2019-05-10
NORTHEASTERN UNIV LIAONING
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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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  • A treatment method for improving magnetically induced strain in polycrystalline nimnga alloys based on stress field training
  • A treatment method for improving magnetically induced strain in polycrystalline nimnga alloys based on stress field training
  • A treatment method for improving magnetically induced strain in polycrystalline nimnga alloys based on stress field training

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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 field of new material technology and provides a processing method for improving the magnetically induced strain of polycrystalline NiMnGa alloy based on stress field training. The method is to smelt Ni, Mn and Ga raw materials and cast them into rods, and then form strong steel rods after directional solidification. Orient polycrystalline materials, and then use A The preferred orientation directions are parallel. A mechanical property testing machine was used to perform stress field training on repeated compression of the cuboid sample. The compression was carried out alternately in two directions. As the number of compressions increased, the twin stress platform of the sample was significantly reduced, thereby improving the magnetic induction of the polycrystalline alloy sample. produce strain.

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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Patent Type & Authority Patents(China)
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 LIAONING