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Verification of Magnetoelastic Martensitic Transformation and Dependence of Crystal Orientations on the Transformation

磁弹性马氏体相变的验证以及晶体取向对相变的依赖性

基本信息

批准号：
60460192
负责人：
SHIMIZU Ken'ichi
金额：
$ 4.93万
依托单位：
The Institute of Scientific and Industrial Research, Osaka Univ.
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

Magnetic field-induced martensitic transformations in polycrystals of an ausaged Fe-33.04Ni-10.17Co-3.94Ti (mass%) alloy have been studied to clarify the influence of magnetic fields on a thermoelastic transformation by means of magnetization measurement, applying pulsed ultra high magnetic fields (the maximum strength is 31.75 MA/m) to the alloy polycrystals. The magnetization measurement was carried out at the Ultra Hihg Magnetic Field Laboratory of Osaka University. The results obtained are summarized below.1. Transformation temperatures have been determined by measuring the electrical resistivity and magnetization as a function of temperature. The determined <M_s> , <A_s> and <A_f> were 127, 60 and 159 K, respectively.2. Spontaneous magnetizations in the austenitic and martensitic states have been obtained as a function of temperature by the magnetization measurement. Difference between the spontaneous magnetizations of the two phases decreases with increasing temperature, and the difference at <M_s> was about 0.3 <(mu)_B> . 3. The magnetic field-induced martensites at temperatures above <A_f> disappeared after removing the magnetic field. That is, a magnetoelastic martensitic transformation was first verified to be realized when a magnetic field higher than the critical one was applied at temperatures above <A_f> and then removed. However, even if such a magnetic field was applied in a temperature range, <M_s> < T < <A_f> , the magnetoelastic martensitic transformation could not perfectly be realized, because some martensites were retained.4. The shift of <M_s> temperature, <DELTA> T, increases with the critical magnetic field to induce the martensites, and the relation between the shift and the critical field forms a curved line with small curvature.5. The amount of the magnetic field-induced martensites increases with the strength of magnetic field irrespective of <DELTA> T, although they behave magnetoelastically.

通过磁化强度测量，对合金多晶施加脉冲超高磁场（最大强度为31.75 MA/m），研究了所用Fe-33.04Ni-10.17Co-3.94Ti (mass%)合金多晶中磁场诱导的马氏体相变，以阐明磁场对热弹性相变的影响。磁化强度测量是在大阪大学超高磁场实验室进行的。所得结果总结如下： 1．通过测量作为温度函数的电阻率和磁化强度来确定转变温度。测得<M_s>、<A_s>和<A_f>分别为127、60和159 K。2．通过磁化测量获得了奥氏体和马氏体状态的自发磁化强度随温度的变化。两相的自发磁化强度之间的差异随着温度的升高而减小，并且<M_s>处的差异约为0.3<(mu)_B>。 3. 去除磁场后，<A_f>以上温度下的磁场诱发马氏体消失。也就是说，首先验证了当在高于<A_f>的温度下施加高于临界磁场的磁场时实现磁致弹性马氏体转变，然后将其去除。然而，即使在<M_s><T<<A_f>温度范围内施加这样的磁场，磁致弹性马氏体相变也不能完美地实现，因为一些马氏体被保留。4． <M_s>温度的偏移<DELTA>T随着临界磁场的增加而增加，诱发马氏体，并且偏移与临界磁场之间的关系形成一条曲率较小的曲线。 5．磁场诱发的马氏体的数量随磁场强度的增加而增加，与<ΔT>无关，尽管它们表现出磁弹性。