颗粒各向异性生长对固态相变动力学的影响

摘要

Based on the statistical analysis of blocking effect arising from anisotropic growth,the anisotropic effect on the kinetics of solid-state transformation was investigated.The result shows that the blocking effect leads to the retardation of transformation and then a regular behavior of varying Avrami exponent.Following previous analytical model,the formulations of Avrami exponent and effective activation energy accounting for blocking Effect were obtained.The anisotropic effect on the transformation depends on two factors,non-blocking factor γ and blocking scale k,which directly acts on the dimensionality of growth.The effective activation energy is not affected by the anisotropic effect.The evolution of anisotropic effect with the fraction transformed is taken into account,showing that the anisotropic effect is more severe at the middle stage of transformation.%基于对颗粒各向异性生长引起阻碍效应的几何概率分析,研究生长各向异性效应对固态相变动力学的影响.结果表明:阻碍效应导致生长速率降低,进而导致Avrami指数的规律变化.根据先前的解析模型,推导动力学参数Avrami指数和总有效激活能的解析表达.各向异性效应对相变的影响不仅取决于非阻碍因子y,还取决于阻碍级数k.各向异性效应直接作用在颗粒生长维度上,却不影响转变过程的总有效激活能.考虑到各向异性生长所引起的阻碍效应与转变分数的演化,发现各向异性效应在相变过程中期最为剧烈.