Ni2MnGa单晶马氏体相变过程摩擦耗能的热动力学计算

根据相界面摩擦原理，在推导出计算Ni₂MnGa系统热动力学参量的一般表示式的基础上，结合马氏体相变温度分别在室温以下、室温附近、室温以上三种非正配分比Ni₂MnGa单晶自发相变应变和交流磁化率随温度变化的测量结果，计算了三种样品马氏体相变过程中界面摩擦所消耗的能量.结果进一步表明正是相变过程中的界面摩擦导致了相变的热滞后，而三种样品马氏体相变过程的摩擦耗能和相变热滞后存在较大差别的原因在于三种样品马氏体相变生成物具有不同的结构. 关键词： 马氏体相变 应变 界面摩擦

Thermodynamic calculation of energy consumed for boundary friction during martensitic transformation in single crystal Ni2MnGa

Based on the boundary friction phenomenological theory,a general equation for calculating the thermodynamic parameters of Ni₂MnGa system was deduced.According to the measured results of the ac magnetic susceptibility or strain during the martensitic transformation for three non-stoichiometric Ni₂MnGa single crystal samples with martensitic transition occurring at temperatures below,near,and above room temperature,respectively,the energies consumed for boundary friction in the three samples during their martensitic transformations were calculated using the general equation.It was also indicated that the thermal hysteresis of martensitic transformation originates from the friction of phase boundary motion;moreover,the large differences of the energy consumed for boundary friction and the thermal hysteresis result from the different structures of martensites produced for the three samples during the martensitic transformation.