通过晶体相场法模拟了与基体三种不同取向圆形晶粒在缩小过程中晶界上的位错湮灭机制与晶界迁移机制。研究结果表明：当圆形晶粒和基体的取向差17◦时，圆形晶粒和基体形成位错核心重叠的大角晶界，用位错模型难以解释该演化过程，但结果表明圆形晶粒半径的平方与演化时间成线性关系，该关系与弯曲晶界迁移理论相互印证；当取向差为4◦时，圆形晶粒和基体形成由分离位错构成的小角晶界，在该晶粒缩小的过程中，位错以径向攀移为主且会发生晶粒转动以调整位错间距，随着位错间距的减小相互靠近的位错发生反应；当取向差为10◦时，晶界既有位错核心重叠较小的部分也有由分离位错构成的部分，在晶粒缩小时晶界演化表现为位错径向攀移和切向运动，两种运动的耦合运动使得能相互反应的位错相互靠近并发生反应。%The phase-field crystal method is used to analysis the dislocation annihilation and grain boundary migration mech-anism in the grain shrink process of the circular grain which has three different misorientations from the matrix grain. Results show that when the misorientation between the circular grain and the matrix grain is 17◦, the structure of grain boundary is composed of dislocations whose cores is so near that can not find a single dislocation. This grain boundary can not be explained by the dislocation model. However the circular grain area decreases linearly with time, which is in good agreement with the classical boundary migration theory. When the misorientation is 4◦, the grain boundary structure is composed of discrete dislocations. Dislocations climb along the radial dierction and the grain rotation occurs for the circular grain to adjust the space of dislocations in the process of circular grain shrinkage. Reactions may take place with the dislocatins becoming closer. For the misorientation of 10◦, portion of the grain boundary is composed of discrete dislocations and portion of dislocations with cores overlapped. Dislocations climb along the radial direction and tangential motion occurs at the same time in the grain shrinkage process. The coupled motion lead to the dislocations becoming close and reacting with each other.
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