Ni_(75)Al_xV_(25-x)合金沉淀相粗化行为的微观相场模拟

MICROSCOPIC PHASE-FIELD SIMULATION OF COARSENING BEHAVIOR OF PRECIPITATES IN Ni_(75)Al_xV_(25-x) ALLOY

基于共格应变的微观弹性理论和微观相场动力学模型,模拟了Ni75AlxV25-x合金沉淀过程的组织演化和粗化行为．结果表明:两种沉淀相颗粒在粗化阶段均表现出明显的取向性．θ相(Ni3V)沿[100]方向的生长趋势明显超过[001]方向, γ′相(Ni3Al)沿(001)方向排列．二相析出顺序与Al含量有关,先析出相的长大和粗化两个阶段比较分明,后析出相的长大和粗化过程同时进行．两种有序相发生粗化以相邻颗粒碰撞并融合为较大颗粒的方式进行．不同浓度的合金两相析出先后顺序及体积分数不同,但最终形貌基本一致,两相均呈长方块状分布,并且具有(001)θ#{100}γ′的取向关系．

Based on the microelasticity theory of coherent strain and the microscopic phase-field dynamic model, the morphology evolution and the coarsening behavior of precipitates in Ni75AlxV25-x alloy were simulated. The two precipitate particles have the obvious orientation when the coarsening happened. The [100] direction of θ phase （Ni3V） is the preferential growth direction and γ＇ phase （Ni3Al） aligned along the （001） directions. The precipitated sequence of the two phases is related to Al content. The growth and coarsening of the early precipitated phase have two evident stages , but growth and coarsening of the late precipitated phase evolved simultaneously. The growth and coarsening of precipitates take place by means of the coalescence between neighboring particles. In despite of the precipitated sequence and the volume fraction are different for the alloys with different concentrations, the morphologies of two phases are almost same at last, which have the quadrate shape, and the orientation relationship of （001）θ ‖ {100}γ＇, exists between two phases.