Ni-Mn基Heusler合金马氏体相变温度与电子密度的关系

价电子浓度和晶格体积是影响Heusler合金马氏体相变温度的两个主要因素.为了研究Ni-Mn基Heusler合金马氏体相变温度的变化规律,我们利用第三主族元素Al,Ga,In分别对Ni44Mn45Sn11合金中的Sn进行替代研究.实验结果表明：Al,Ga和In与Sn相比具有较少的价电子和较小的离子半径,替代导致合金价电子浓度降低和晶格体积收缩,但马氏体相变温度并不随着价电子浓度和晶格体积单调地上升或下降,价电子浓度和晶格尺寸机制均不能独立地解释Ni44Mn45Sn10R（R=Al,Ga,In和Sn）合金中的马氏体相变温度变化规律.综合价电子浓度和晶格尺寸因素,我们提出用电子密度可很好地解释Ni-Mn基铁磁形状记忆合金体系中马氏体相变温度随着电子密度的升高而升高的变化规律.

The relationship between MT temperature and electron density of Ni-Mn based Heusler alloys

Valence electron concentration and cell volume are the two main factors influencing MT temperatures for Ni-Mn based Heusler alloys. In order to investigate the mechanism of MT temperatures in Ni-Mn alloys, we study the substitution of A1, Ga and In elements of the III main group for Sn in the Ni44Mn45Sn11 alloy at an off- stoichiometric composition. The result indicates that it has smaller ionic radius and fewer valence electrons for A1, Ga and In than that of Sn and induce a reduction on valence electron and the volume of unite cell. However, the MT temperatures neither show a monotonous reduction nor enhancement with the two factors, which indicate that the effect of either valence electron concentration or cell volume can explain the variations of MT temperatures in Ni44Mn45Sn10R （R=A1, Ga, In and Sn）. Combining the factors of valence electron concentration and cell volume, electron density is proposed more proper to describe the variation of MT temperatures in Ni-Mn ferromagnetic shape memory alloys, in which MT temperatures increase with increasing the density of electron.