论文部分内容阅读
通过研究铁磁性金属间化合物Ni2 +xMn1-xGa(x =- 0 1,0 ,0 0 8,0 13,0 18,0 2 )和Ni2 -xMn1+x/ 2 Ga1+x/ 2(x =- 0 1,0 ,0 0 4,0 0 6 ,0 1)两个系列多晶样品的交流磁化率随温度的变化行为 ,得到了化合物在不同组分下的马氏体相变温度TM 和居里温度TC.发现随着Ni成分的增加 ,前者的马氏体相变温度Tm 增加 ,而居里温度TC降低 ,后者的马氏体相变温度Tm 和居里温度TC 均是先增大后减小 .报道了Tm 在室温附近的单晶样品Ni52 Mn2 4Ga2 4 的磁场增强双向形状记忆效应 .发现伴随着马氏体相变 ,样品在 [0 0 1]方向可产生 1 2 %的收缩 .如果在该方向施加 1 2T的偏磁场可以使该应变值增大到 4 0 % .而垂直于 [0 0 1]方向施加 1 2T的偏磁场时 ,在 [0 0 1]方向产生1 6 %的膨胀 .阐明了产生大应变的原因并非相界移动 ,而是单晶的杂散内应力小和外加磁场通过孪晶界移动使马氏体变体重组的共同结果 .
The ferromagnetic intermetallic compounds Ni2 + xMn1-xGa (x = - 0 1,0,0,08,0 13,0 18,0 2) and Ni2-xMn1 + x / 2 Ga1 + x / 2 - 0 1,0, 0 0 4,0 0 6, 0 1) The changes of the AC susceptibilities with temperature of the two series of polycrystalline samples show that the martensitic transformation temperatures TM and Curie temperature TC. It is found that with the increase of Ni composition, the former increases the martensite transformation temperature Tm and the Curie temperature TC decreases, while the latter forms the martensite transformation temperature Tm and Curie temperature TC first And then decreased.At the same time, it is reported that the field-enhanced two-way shape memory effect of the single crystal sample Ni52Mn2 4Ga2 4 near Tm at room temperature is reported.The samples are found to have a 12% increase in the [0 0 1] direction with the martensitic transformation Shrinkage.If a bias field of 1 2 T is applied in this direction to increase the strain value to 40%, and a bias field of 1 2 T perpendicular to the direction of [0 0 1] yields 1 in the direction of [0 0 1] 6% .It is clarified that the cause of the large strain is not the phase boundary, but the common result that the stray internal stress of the single crystal is small and the applied magnetic field recombine the martensite by the twin boundary.