Prediction of grain structure evolution during rapid solidification of high energy density beam induced re-melting
Prediction of grain structure evolution during rapid solidification of high energy density beam induced re-melting
复制标题
高能量密度束诱导重熔快速凝固过程中晶粒结构演化的预测
DOI：
10.1016/j.matdes.2018.03.036
复制
发表时间：
2018
影响因子：
8.4
通讯作者：
Flint T
中科院分区：
文献类型：
--
作者：
Flint T
在集中热源存在下的晶界迁移是一个复杂的过程，其对所得材料性质具有相当大的影响。一个相场模型，提出了将热梯度和曲率驱动力项，以预测如何多晶网络的演变，由于这种热源的应用，作为晶界迁移，由于局部边界曲率和随时间变化的热梯度。各种热的情况下进行了调查，在两个和三个维度。这些方案包括部分和完全穿透激光诱导熔化，线性变化的时间无关的热场的应用，以及连续的熔化事件，其中区域经历多个熔化和固化循环。相场法预测的微观结构之间的比较，在各种热的情况下，同意与常见的现象。特别有趣的是，能够解释晶粒形态的差异之间的全熔透和部分熔透焊缝使用相场模型和相关的驱动力大小之间的两种情况。该模型预测了在经历多次熔化事件的区域中晶界网络的恢复，并解释了由于局部曲率和热梯度效应导致的晶粒形态的差异。
Grain boundary migration in the presence of concentrated sources of heat is a complex process that has a considerable impact on resultant material properties. A phase field model is presented incorporating thermal gradient and curvature driving force terms to predict how a poly-crystalline network evolves due to the application of such heat sources, as grain boundaries migrate due to local boundary curvature and time-varying thermal gradients. Various thermal scenarios are investigated, in both two and three dimensions. These scenarios include both partial and full penetration laser induced melting, the application of a linearly varying time-independent thermal field, and successive melting events where regions experience multiple melting and solidification cycles. Comparisons are made between the microstructures predicted by the proposed phase field method, during the various thermal scenarios, that agree with commonly observed phenomena. Particularly interesting is the ability to explain the differences in grain morphology between the full penetration and partial penetration welds using the phase field model and associated driving force magnitudes between the two scenarios. The model predicts the restoration of grain boundary networks in regions experiencing multiple melting events, and explains the differences in grain morphology due to the local curvature and thermal gradient effects.