哈斯勒合金Ni-Mn-Ga中马氏体相变热力学研究

Thermodynamics Research of Martensitic Phase Transition in Ni-Mn-Ga Heusler Alloys

通过交流磁化测量手段分析了Ni51.5Mn24Ga24.5单晶样品与Ni47.5Mn27.5Ga25多晶样品的马氏体相变温度和热滞后温度,并基于相界摩擦理论计算了样品在无外加负载情况下马氏体相变过程中相界摩擦所产生的能耗Fr.结果表明,两样品克服相界摩擦所产生的能耗分别为19.96 J/mol和34.93 J/mol,仅占马氏体相变潜热的很少一部分.此外,通过比较样品的热力学参数,相变的热滞后正是起源于马氏体相变过程中的相界摩擦,从而进一步说明了相界摩擦理论较好地解释了Ni-Mn-Ga合金在马氏体相变过程中的热滞后问题.

The martensitic transition temperature and thermal hysteresis temperature in Ni51.5 Mn24Ga24.5 single-crystalline and Ni47.5Mn27.5Ga25 polyerystal were investigated by means of AC magnetic susceptibility. According to the boundary frieation phenomenologieal theory, the energy was calculated consumed for phase boundary motion in these free samples during martensitie transformation. It has been found that the energy consumed for phase boundary motion is 19. 96 J/mol and 34. 93 J/mo｜, respectively, which is only a small part of the latent heat of martensitie transformation. Furthermore, comparative thermodynamic parameter indicated that thermal hyseresis of martensitie transformation originates from the friction of phase boundary motion, which in turn accounts for the thermal hysteresis during transformation in Ni-Mn-Ga alloys quite well.