共格畸变影响沉淀相形貌的计算机研究

Computer Simulation of Strain-Induced Morphological Transformation of Coherent Precipitates

利用微观扩散方程 ,结合微观弹性力学理论 ,对二元立方模型合金的沉淀过程进行计算机模拟 ,通过取不同的应变能参数B ,研究共格畸变对沉淀相形貌的影响。研究发现 :当忽略应变能时 ,沉淀相为随机分布的等轴颗粒 ,呈各向同性特征 ,其粗化遵循奥斯瓦尔德熟化机制 :小颗粒溶解 ,大颗粒长大。当考虑应变能时 ,沉淀相为片状 ,趋于沿弹性 <0 1>“软”方向排列 ,呈各向异性特征 ,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 ,而对于同一行或列上的颗粒又存在小颗粒溶解、大颗粒长大现象。由模拟结果还可看出 :在共格畸变作用下 。

The coherent elastic strain-induced morphological transformation of a binary cubic model alloy was simulated under different strain energy parameters, the microscopic diffusion equation was used combined with the theory of microscopic elasticity. The results show: when the strain energy is neglected, randomly distributed equiaxed particles were obtained with isotropic characteristics, its coarsening follows the Ostwald ripening mechanism: smaller particles dwindle and larger particles grow; When the elastic strain is considered, plate precipitates tend to align along the elastically soft directions <01> and <10> with anisotropic characteristics. Particles lying in the soft directions grow and coarsen further. Particles lying out of the soft directions dwindle. while coarsening of the particles sitting in the same row or column follows: smaller particles shrink and larger ones grow. It's also found that the phase decomposition process slow down obviously in the presence of the elastic strain.