A predictive model for microstructure evolution in metallic multilayers with immiscible constituents
A predictive model for microstructure evolution in metallic multilayers with immiscible constituents
复制标题
具有不混溶成分的金属多层微观结构演化的预测模型
DOI：
10.1016/j.actamat.2012.08.062
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发表时间：
2012-11
期刊：
影响因子：
9.4
通讯作者：
Xuejun Jin
中科院分区：
文献类型：
--
作者：
Haibo Wan;Yao Shen;Jian Wang;Zhiqiang Shen;Xuejun Jin
专注于层状结构的热稳定性，我们开发了一个预测模型来研究具有不同形态（包括对齐和经典交错晶粒几何形状）的金属多层的微观结构演化。我们发现，当每个上层中的晶粒与下层的面内晶粒尺寸的相对移动小于一半时，在多层中实验观察到的锯齿形微观结构就会形成。在这个形成过程中，非平衡三重结在相间和晶界张力不平衡的驱动下移动，这对应于经典开槽理论的延伸。数值模拟表明，三结的有限迁移率可以有效地阻碍凹槽的发展，这表明在假设无限三结迁移率的情况下，凹槽深度的经典 t1/4 依赖性在低温下预测夹断时间可能存在问题。此外，根据晶粒尺寸的纵横比和两个最近的三重结之间的距离与面内晶粒尺寸的比率，开发了 Cu/Nb 体系中层状结构稳定性的图。基于简化的几何考虑，还为具有相似晶界能量的多层提出了这种稳定性的标准。该图和简单准则都与 Cu/Nb 多层的实验非常一致。
Focussing on the thermal stability of layered structures, we developed a predictive model to study the microstructure evolution of metallic multilayers with different morphologies including aligned and classical staggered grain geometries. We found that the zig-zag microstructure experimentally observed in multilayers forms when grains in each upper layer have a relative shift less than half the in-plane grain size to the lower layer. During this formation process, the non-equilibrium triple junctions move, driven by the imbalance of tensions of interphase and grain boundaries, corresponding to an extension to classical grooving theory. Numerical simulations show that a finite mobility of the triple junction can effectively impede the development of grooves, suggesting that the classical t1/4dependence of groove depth with the assumption of an infinite triple junction mobility might be questionable at low temperatures to predict the time to pinch-off. Further, a map for the stability of layered structure in Cu/Nb system is developed in terms of the aspect ratio of grain dimensions and the ratio of the distance between two nearest triple junctions to the in-plane grain size. A criterion for this stability is also proposed for multilayers with similar grain boundary energies based on simplified geometrical consideration. Both the map and the simple criterion are in good agreement with the experiments for Cu/Nb multilayers.
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