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首页> 外文学位 >The effect of magnetic field on shape memory behavior in Heusler-type nickel(,2)manganese-gallium-based compounds.
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The effect of magnetic field on shape memory behavior in Heusler-type nickel(,2)manganese-gallium-based compounds.

机译：磁场对Heusler型镍（，2）锰-镓基化合物的形状记忆行为的影响。

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摘要

Shape memory alloys (SMAs) have excellent mechanical properties showing large stroke and high power density when used as actuators. In terms of response speed, however, conventional SMAs have a drawback due to the isothermal nature of the associated phase transformation.; A new type of SMA, called ferromagnetic SMA, is considered to replace conventional SMAs and is hoped to overcome such a slow response drawback by changing driving mode of shape memory behaviors from thermal to magnetic. The new type of ferromagnetic SMAs is expected to exhibit not only a large displacement but also rapid response when magnetic field is applied and removed. There are three kinds of ferromagnetic SMAs and among them, Ni2MnGa-based compounds exhibit prominent shape memory effects and superelasticity. In this study, Ni2MnGa-based alloys were chosen and studied to characterize shape memory behavior upon the application and removal of magnetic field. The relevance of the magnetic field-induced shape memory behavior to the magnetization process was investigated by using transformation and/or the movement of martensite variant interfaces.; Two mechanisms have been proposed for controlling magnetic field-induced shape memory behaviors. One mechanism is related to shape memory behavior associated with magnetic field-induced martensitic transformation. The other is related to the rearrangement of martensite variants by magnetic field application.; Magnetic field-induced martensitic transformation and shape memory effects for single- and poly-crystalline Ni2MnGa alloys were investigated under various conditions. In single crystalline specimens, it was observed that considerable strain changes are a function of magnetic field at temperatures below Mf (martensite finish temperature). Such strain changes, by application and subsequent removal of magnetic field, may be attributed to the martensite variant motion at lower temperatures than Mf. Magnetic field application made a significant contribution to the martensite transformation and related strain changes (0.3%–0.82%) at temperatures above Af (austenite finish temperature) in some polycrystalline Ni2MnGa alloys, where austenite and martensite phases possess paramagnetic and ferromagnetic properties, respectively.
机译：形状记忆合金（SMA）具有出色的机械性能，当用作执行器时具有大行程和高功率密度。然而，就响应速度而言，由于相关相变的等温特性，传统的SMA具有一个缺点。一种新型的称为铁磁SMA的SMA被认为可以代替传统的SMA，并希望通过将形状记忆行为的驱动模式从热更改为磁来克服这种慢响应的缺点。当施加和去除磁场时，新型铁磁SMA不仅显示出大位移，而且响应迅速。铁磁SMA共有3种，其中Ni 2 MnGa基化合物表现出突出的形状记忆效应和超弹性。在这项研究中，选择并研究了Ni 2 MnGa基合金，以表征施加和去除磁场后的形状记忆行为。通过使用马氏体变体界面的转变和/或运动研究了磁场诱导的形状记忆行为与磁化过程的相关性。已经提出了两种机制来控制磁场引起的形状记忆行为。一种机制与与磁场引起的马氏体转变有关的形状记忆行为有关。另一个与通过磁场施加使马氏体变体重新排列有关。研究了单晶和多晶Ni 2 MnGa合金在各种条件下的磁场诱导马氏体相变和形状记忆效应。在单晶样品中，观察到相当大的应变变化是在低于M （马氏体终点温度）的温度下磁场的函数。通过施加和随后去除磁场，这种应变变化可能归因于马氏体变体在比M 更低的温度下运动。在某些多晶Ni 2 的A f （奥氏体终点温度）以上的温度下，磁场的施加对马氏体相变和相关应变变化（0.3％–0.82％）做出了重要贡献。 > MnGa合金，其中奥氏体和马氏体相分别具有顺磁性和铁磁性。

著录项

  • 作者

    Jeong, Soon-Jong.;

  • 作者单位

    University of Washington.;

  • 授予单位 University of Washington.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2000
  • 页码 262 p.
  • 总页数 262
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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