共格沉淀相粗化行为的计算机模拟研究

Computer Simulation of Coarsening Behavior of Coherent Precipitants

摘要:

将微观弹性应变能理论和微观扩散方程相耦合，建立起时效过程微观晶格动力学模型。对溶质浓度为14at％的二元立方点阵模型合金的共格沉淀粗化行为进行模拟。研究发现：该合金沉淀机制以形核长大为主，兼有失稳分解特征；由于共格失配，沉淀相为片状，趋于沿弹性软化方向排列。其粗化作为伴随过程进行，位于软方向上的颗粒继续长大和粗化，位于软方向外的颗粒逐渐消失；而位于同一行或列上的颗粒则遵循：小颗粒溶解，大颗粒长大。

Abstract:

The microscopic lattice kinetic model of aging process was build, using the coupling of the theory of microscopic elastic energy and microscopic diffusion equation. Taking a binary cubic model alloy with 14% (solute atom percent) as a example, the coarsening behavior of coherent precipitants was simulated. The results show that the main precipitation mechanism is nucleation and growth, while transient spinodal decomposition can also occur; In the presence of coherent mismatch, plate-like precipitants are formed, and tend to align along the elastically soft directions. During its coarsening process, particles lying in the soft directions grow and coarsen further, particles lying out of the soft directions dwindle. The coarsening process of the particles sitting in the same row or column obey that smaller particles shrink and larger ones grow.