Origin of chessboard-like structures in decomposing alloys. Theoretical model and computer simulation
Origin of chessboard-like structures in decomposing alloys. Theoretical model and computer simulation
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DOI：
10.1016/s1359-6454(97)00455-2
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发表时间：
1998-05-01
期刊：
影响因子：
9.4
通讯作者：
Khachaturyan, AG
中科院分区：
文献类型：
--
作者：
Le Bouar, Y;Loiseau, A;Khachaturyan, AG
被认为是一个棋盘状结构的形成过程中观察到的沉淀相的几个取向变体的合金相干分解的机制。它是基于在一个最佳模式的沉淀相的取向变体的空间重排实现的一致性应变的住宿。基于组成和长程有序参数分布的连续随机场动力学方程，建立了有序四元相沉淀的计算模型。其数值解描述了从形核到粗化的微观结构的时空演化。它示出的棋盘状的微观结构是由应变驱动的，自组装的取向变体的沉淀相，刻面的垂直于弹性软方向的平面。这种微结构的粗化通过图案中整排“瓦片”的随后消失而发生。用透射电镜观察了Co-Pt合金中棋盘结构的形成。在（CuAu）（1-x）-Pt-x和Co-39.5-Pt-60.5两种合金中，模拟结果与实验观察结果非常吻合。(C)1998年冶金学报
The mechanism of formation of a chessboard-like structure observed during coherent decomposition in alloys with several orientation variants of the precipitate phase is considered. It is based on the accommodation of coherency strain achieved by spatial rearrangement of orientation variants of the precipitate phase in an optimal pattern. The computational model of precipitation of the ordered tetragonal phase, based on the continuum stochastic field kinetic equations for the composition and long range order (Iro) parameters profiles, is formulated. Its numerical solution describes the spatial and temporal evolution of the microstructure, from nucleation to coarsening. It is shown that the chessboard-like microstructure is produced by strain-driven, self-assembling of orientation Variants of the precipitate phase, faceted by the planes normal to the elastically soft directions. Coarsening of such a microstructure occurs by consequent disappearance of entire rows of "tiles" in the pattern. TEM observations of the formation of the chessboard structure in the Co-Pt alloys are performed. The simulation results are in excellent agreement with experimental observations in both the (CuAu)(1-x)-Pt-x and Co-39.5-Pt-60.5 alloys. (C) 1998 Acta Metallurgica Inc.