温度梯度对晶粒生长行为影响的相场模拟

利用相场法建立了一个可应用于研究温度梯度影响下的晶粒生长行为的二维模型,模拟了多晶材料退火过程中由温度梯度引起的非均匀晶粒生长和定向晶粒生长行为.结果表明:退火过程中,在静态温度梯度的影响下,体系的晶粒呈现不均匀生长,且从晶粒生长指数来看,不同程度地偏离了正常晶粒生长;在动态温度梯度的影响下,体系内部常出现柱状晶粒生长,柱状晶粒前端持续生长至温度最高位置;柱状晶粒生长与动态热源的移动速率密切相关,只有当动态热源的移动速率处于最小和最大晶粒生长速率之间时,柱状晶粒才会出现. 关键词： 晶粒生长 相场法 晶界迁移率 局部退火

Effect of temperature gradient on grain growth behavior from phase field simulations

A 2D model is developed to investigate the grain growth behavior under the influence of temperature gradient using the phase field method. The model is used to simulate the effect of temperature gradient on the nonuniform and directional grain growth behavior during annealing of polycrystalline materials. The results show that the static temperature gradient leads to the nonumiform grain growth, and that the grain growth exponent deviates from that of normal grain growth. In the case of annealing with a moving temperature gradient, the columnar grains may develop towards the locations with the highest temperature in the heated zone. Moreover, the grain growth behavior is closely related to the moving speed of the moving heated zone. Columnar grains occur only when the moving speed of the heated zone is higher than the minimum grain growth rate but lower than the maximum grain growth rate.