I题 目晶粒演变过程相场模拟初步探索摘 要本文采用相场方法对晶粒的演变过程进行了初步的探索。相场法基于弥散界面模型，认为相界面是一个有厚度的连续变化区域。其主要思想是引入相场参数西来跟踪相界面的移动，通过直接求解Cahn-Hilliard 非线性扩散方程得到微观组织形貌的演化过程。根据Cahn-Hilliard 方程，建立了晶粒演变相场模型，实现了晶粒演变数值模拟。对纯铁固溶处理后，未固溶处理的纯铁的晶粒最大尺寸为76.88μm 。固溶处理1h的晶粒直径最大，其最大晶粒尺寸为83.07μm 。固溶处理2h的晶粒最大尺寸为74.09μm 。固溶处理3h的晶粒最大尺寸为65.89μm 。所以保温一小时的纯铁晶粒尺寸最大，效果较好。然后编制了均匀温度场下晶粒演变过程计算机模拟程序，并对纯铁固溶和热处理晶粒演变进行了相场模拟，发现模拟结果与试验结果一致。由于相场方程是非线性方程，非线性方程对于边界设置的敏感度较高，探索了不同的参数值对晶粒形貌的影响，模拟不同参数值发现了参数值的不同对晶粒的形貌影响较大。关键词：相场方法；晶粒演变；Cahn-Hilliard；晶粒形貌IIAbstractIn this paper, the phase field method is used to explore the evolution process of grain.The phase field method is a diffuse interface model, and the phase interface is a continuously varying region having a thickness.The phase field parameters are used to determine the movement of the phase interface, and the Cahn-Hilliard nonlinear diffusion equation is solved to obtain the evolution process of the microstructure.Using the Cahn-Hilliard equation, the grain evolution phase field model is used to simulate the grain evolution.After the solution treatment of pure iron, the maximum size of the crystal grains of the undissolved pure iron was 76.88 μm.The maximum grain size of solution treatment for 1h was 83.07 μm.The maximum grain size of the solution treated for 2h was 74.09 μm. The maximum grain size of the solution treated for 3h was 65.89 μm.Therefore, the effect of keeping the pure iron grain size for one hour is be...
