单晶Ni_(52)Mn_(24)Ga_(24)中马氏体变体择优取向的物理表征

Characterization of preferential orientation of martensitic variants in Ni_ (52)Mn_(24)Ga_(24) single crystal

利用各种实验手段对Ni52 Mn2 4 Ga2 4 单晶中马氏体变体的择优取向进行了表征 .针对金相观察、磁场干预的相变应变、磁感生应变等实验结果 ,分析了马氏体相变过程变体自发择优取向和磁诱导择优取向的机理 .根据不同方向磁场干预相变应变的结果 ,计算了Ni52 Mn2 4 Ga2 4 单晶中等效取向内应力的大小约为 2 .4 5MPa .从变体择优取向造成的有效弹性和磁畴分布两个方面 ,对单晶样品在 [0 0 1]和 [0 10 ]两个等价的晶体学方向上磁感生应变特性的差别 ,包括最大应变值、饱和场、滞后效应和起始磁场数值的参数 ,进行了分析和讨论 .

The preferential orientation of martensitic variants in the single crystal Ni 52Mn 24Ga 24 has been characterized by various methods, such as optical microscopy observation, strain measurement, and magnetic field-induced strain (MFIS). The origin of the spontaneous preferential orientation of variants was attributed to the internal stress with a magnitude of about 2.45 MPa, as calculated based on the experimental data. We found that the preferential orientation of variants produced the anisotropy, different effective elastic constants and distribution of magnetic domain, between two equivalent crystallographic directions of [001] and [010]. The resulting MFIS properties, such as saturated MFIS, saturated field, hysteresis effect and initial magnetic field have been discussed in detail.