形状记忆材料的热力学设计

Thermodynamic Design for Shape Memory Materials

以新一代溶液模型考察了合金元素对Fe-Mn-Si基合金层错能的影响,并预测了Fe-Mn-Si合金面心立方(fcc)→密排六方(hcp)马氏体的相变温度.应用规则溶液模型计算了含Ce和Y的ZrO2基陶瓷四方(t)→单斜(m)马氏体相变的自由能,结合测得ZrO2基陶瓷的强度,预测了马氏体相变的开始温度.对Ni-Mn-Ga磁驱动记忆合金的磁性转变温度TC、体心立方至体心正方(bcc→bct)马氏体相变温度Tmart和饱和磁化强度MS与成分的关系进行了优化,提出了具有较佳综合性能的成分范围.应用热力学方法对Fe-Mn-Si基合金、ZrO2基陶瓷和Ni-Mn-Ga铁磁合金等形状记忆材料作出的成分设计均与实验结果符合较好.

The effects of alloying elements on the stacking fault energy in Fe-Mn-Si based shape memory alloys were investigated by a new generation solution model. Gibbs free energy change for tetragonal(t) to monoclinic(m) martensitic transformation in ZrO2 based ceramics containing CeO2 and Y2O3 was calculated by the regular solution model. The martensitic transformation temperature was predicted, combined with the measured strength for this ZrO2 containing ceramic. The relationship between compositions and magnetic transition temperature Tc, bcc&rarrbct martensitic transformation temperature Tmart, and saturation magnetization Ms in Ni-Mn-Ga ferromagnetic shape memory alloys was optimized empirically. The thermodynamic predictions are in good agreement with the experimental results.