摘要
在单晶样品Ni52 Mn2 4 5Ga2 3 5中观察到了单纯由温度诱发的完全的热弹性中间马氏体相变 ,测定了母相和中间马氏体相的晶体结构和晶格参数 .通过对研磨成不同晶粒度大小的单晶样品的研究 ,发现晶粒度小于 5 0 μm时 ,由于机械研磨引入的内应力可以使中间马氏体相变消失 .但这种引入的内应力并不引起马氏体相变温度的明显改变 .计算了不同晶粒度大小的样品由于机械研磨引起的微观应变和引入的微观内应力 .分析指出 ,马氏体相变路径的选取与机械研磨引入的内应力大小密切相关 .
A complete thermally induced intermartensitic transformation has been observed in the Ni 52Mn 24.5Ga 23.5 single crystal, a ferromagnetic shape memory alloy. The crystal structure and the lattice parameters were determined for the parent phase and the intermartensite phase, respectively. It is noteworthy that the appearance of the intermartensitic transformation strongly depends on the internal stress in the crystal. Based on the investigation of temperature dependence of ac susceptibility in single crystals with different particle sizes, we found that when the sample particle size was getting smaller than 50 μm, the grind-induced internal stress would lead to the disappearance of the intermartensitic transformation. Nevertheless, the internal stress had no influence on the martensitic transformation temperature. The stress level in the ground powders was also studied. The critical average grind-induced internal stress to restrain the intermartensitic transformation was calculated to be 90 MPa.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2002年第3期640-644,共5页
Acta Physica Sinica
