夹杂物/析出相尺寸对晶内铁素体形核的影响

建立了铁素体在夹杂物/析出相上形核的物理模型.从相变形核热力学和动力学机理出发,研究了晶内铁索体在夹杂物/析出相上的形核过程,分析了夹杂物/析出相的尺寸、界面性质等因素对晶内铁索体相变形核的影响.结果表明,与铁素体具有较小接触角的夹杂物/析出相更有利于晶内铁素体形核.当夹杂物与基体的界面性质一定时,铁索体在夹杂物上形核的难易程度主要取决于夹杂物的尺寸(夹杂物的曲率半径),尺寸过小不利于铁索体形核,尺寸过大对形核贡献较小.对任意类型的夹杂物/析出相,给出了其计算最优尺寸的方法,计算结果与实际吻合良好.

Effect of the Inclusions/precipitates size on the Intragranular ferrite nucleation

Based on the classical nucleation theory a physical model was established to evaluate the effectiveness of intragranular ferrite nucleating at inclusions/precipitates. The influences of inclusion size, interfacial energy and contact angle on the ferrite nucleation rate were studied. Theoretical analysis indicates that the inclusions exhibiting lower contact angle with ferrite are most effective in promoting the nucleation of intragranular ferrite. Given the inclusion-matrix interfacial properties, the effectiveness of ferrite nucleation depends on the inclusion size. For arbitrary type of inclusion/precipitate, there exists an optimum size range in theory with maximum ferrite nucleation rate. The method for calculating this optimum size of inclusion was given, and the results showed a good agreement with experimental observations.