单晶Ni52Mn16．4Fe8Ga23．6的磁控形状记忆效应和磁感生应变

用磁悬浮冷坩埚提拉设备沿[001]方向生长了组分为Ni52Mn16.4Fe8Ga23.6的单晶,通过磁增强相变应变和磁感生应变的测量研究了该材料磁控形状记忆效应和磁感生应变的温度稳定性。结果发现该材料不但具有大的自发相变应变、磁增强相变应变和磁感生应变,而且磁感生应变具有很好的温度稳定性,从265K到100K,饱和磁感生应变的最大减小量不超过10％。另外,实验也发现磁感生应变量最大的方向是沿晶体母相的[001]方向(即单晶生长方向)。根据合金形状记忆的特点和磁场诱导应变的机理对实验结果进行了分析和讨论。

Field-Controlled Shape Memory Effect and Temperature Stability of the Magnetic-Field-Induced Strain in Ni52Mn16.4Fe8Ga23.6 Single Crystal

Ferromagnetic Ni-Mn-Fe-Ga single crystal of a pseudoquaternary Heusler alloy has been invested as a new magnetic field control actuator material. A single crystal of Ni52Mn16.4Fe8Ga23.6 was grown in [001] direction of the cubic parent phase by the Czochralski method. The field-controlled shape memory effect and the temperature dependent of the magnetic-field-induced strain (MFIS) in Ni52Mn16.4Fe8Ga23.6 single crystal were investigated by measuring the field enhanced transformation strain and the MFIS with a magnetic field applied in different directions. The results show that such material combined with the martensitic transformation can produce the large field-enhanced transformation strain and the large MFIS. It is found that the MFIS is almost temperature independent, the maximum decreasing magnitude of the saturated MFIS is less than 10% from 265 K to 100 K. In addition, the direction in which the MFIS has the largest value is always the [001], namely the growth direction of the crystals. The results are discussed with reference to the shape memory characteristics of the alloys and the mechanism of the preferentially orientation of martensitic variants.