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通过交流磁化率、电阻、有无磁场下的预相变应变、磁致伸缩和磁化强度测量 ,系统研究了近正配分比Ni50 5Mn2 4 5Ga2 5单晶的预马氏体相变特性 .在自由样品中观察到预马氏体相变应变 .在预相变点 ,沿 [0 10 ]方向施加大小约为 80kA m的磁场 ,在晶体母相的 [0 0 1]方向上获得了高达 5 0 5ppm的磁致伸缩 ,该值是相同条件下晶体母相磁致伸缩量的 5倍多 .同时 ,报道了不同方向磁场对预相变应变干预的结果 .利用软模凝结的概念和依据单晶生长的特点 ,分析了预相变应变产生的机理 .而磁场干预预相变应变的机理是磁场增大的磁弹耦合导致的晶格形变与材料内禀形变的竞争 .利用磁性测量结果证实和解释了预相变过程中 [0 0 1]和 [0 10 ]轴方向间进一步增大的各向异性 .进而对磁场沿 [0 0 1]和 [0 10 ]两个晶体学方向所导致的应变特性的差别 ,包括最大磁致伸缩、饱和预相变应变、饱和场等 ,进行了分析和讨论
The pre-martensitic transformation properties of Ni50 5Mn2 4 5Ga2 5 single crystal with near normal distribution ratio were systematically investigated by AC susceptibility, resistance, pre-phase strain, magnetostriction and magnetization measurements in the presence or absence of magnetic field. The pre-martensitic transformation strain was observed in the sample.At the pre-transformation point, a magnetic field of about 80 kA m was applied in the [0 10] direction and up to 50 in the [0 0 1] direction of the crystalline mother phase 5ppm, which is more than 5 times of the magnetostriction of the crystalline mother phase under the same conditions.At the same time, the results of intervened by different directions of the magnetic field on the pre-phase strain were reported.The concept of using the soft-mold condensation and the single crystal The mechanism of pre-phase strain transformation is analyzed.The mechanism of pre-phase transformation strain induced by magnetic field is the competition between the lattice deformation and the material intrinsic strain caused by the increase of magnetic field.Based on the magnetic measurement results, Explained the further increase of anisotropy between the [0 0 1] and [0 10] axis directions during the pre-phase transformation, and further analyzed the magnetic field along [0 0 1] and [0 10] two crystallographic directions Differences in strain characteristics include maximum magnetostriction and saturation pre-phase Strain, saturation field, etc., are analyzed and discussed