Development of the new method to investigate the phase transformations based on the computational scientific approachs.

(1)基于非线性演化方程（宫崎）的相分解的计算机模拟.研究了真实的合金系（如Al-Zn，Cu-Co，Fe-Mo，Fe-Al-Co，Fe-Cr和III-V族化合物半导体等）相分解的时间演化.进行了实验研究。基于本研究发展的相场法，对这些合金体系的微观组织变化动力学进行了模拟。计算得到的微结构形貌特征与实验结果吻合较好。(2)临界现象的计算分析（Mohri）：利用集团变分和路径概率方法，数值计算了相变点附近有序-无序相变的磁化率和弛豫时间。当相变类型为一级时，磁化率向失稳温度方向发散。众所周知，临界慢化将发生在二级相变点。通过计算发现，即使是一级相变也会出现类似的现象。相变点附近自由能的平坦性是上述现象的根源。(3)对马氏体相变的类橡胶行为进行了理论研究，成功地模拟了马氏体相变的类橡胶行为。从相场型演化方程出发，考虑双边界运动，推导出应力应变场的本构方程。通过数值模拟，预测了应力-应变曲线及其频率依赖性。

(1) Computer simulation of the phase decomposition based on the non-linear evolution equation (Miyazaki).The time evolution of the phase decomposition in the real alloy system (such as Al-Zn, Cu-Co, Fe-Mo, Fe-Al-Co, Fe-Cr and III-V compound semiconductor, etc.) was investigated experimentally. The dynamics of the microstructure changes for those alloy systems were simulated on the basis of the Phase-field Method developed by the present research. The morphological feature of the calculated microstructures were in good agreement with the experimental results.(2) Computational analysis of the critical phenomena (Mohri).The susceptibility and relaxation time for the order-disorder phase transition near the transition point were investigated by the Cluster Variation and Path Probability Method, numerically. The susceptibility diverged toward the spinodal disordering temperature when the transition type is first order. It is well known that the critical slowing down will occur at the second order phase transition point. We found that the similar phenomenon will take place even for the first order phase transition by our calculation. The flatness of the free energy at the vicinity of the transition point would be the origin for the phenomena above mentioned.(3) Theoretical investigation for the rubber-like behavior of Martensitic transformation (Ohta).The rubber-like behavior of Martensitic transformation was simulated, successfully. The constitutive equations for the stress and strain field were deduced from the phase field type evolution equations with considering the twin boundary motion. The stress-strain curve and its frequency dependence were predicted by the numerical simulation.