烧结细观动力学Monte Carlo模型中的应变
Strain in the mesoscale kinetic Monte Carlo model for sintering
摘要：
从微观结构模拟使用的介观尺度动力学蒙特卡罗（kMC）模型的固态烧结测量收缩应变进行了讨论。该模型使用数字化的离散位点（颗粒或孔隙位点）来表示微观结构。用于通过空位湮灭来模拟致密化的算法去除了晶界处的孤立孔隙位点，并使从空位延伸到烧结压坯表面的位点列塌陷，穿过最近晶粒的质心。使用这种算法，现有的已发表的kMC模型显示，产生各向异性的应变均匀粉末压坯的纵横比不同的单位。结果表明，线方向偏置收缩应变的紧凑尺寸的纵横比成比例。提出了一种新的算法，纠正这种偏见的应变，崩溃的列的方向是通过选择一个随机的样本面，随后在该面上的随机点作为端点的湮灭路径具有相等的概率。该算法在数学上和实验上表明，导致所有样品的各向同性应变，而不管它们的尺寸。最后，微观结构的演变被证明是相似的新的和旧的湮灭算法。
英文摘要：
Shrinkage strains measured from microstructural simulations using the mesoscale kinetic Monte Carlo (kMC) model for solid state sintering are discussed. This model represents the microstructure using digitized discrete sites that are either grain or pore sites. The algorithm used to simulate densification by vacancy annihilation removes an isolated pore site at a grain boundary and collapses a column of sites extending from the vacancy to the surface of sintering compact, through the center of mass of the nearest grain. Using this algorithm, the existing published kMC models are shown to produce anisotropic strains for homogeneous powder compacts with aspect ratios different from unity. It is shown that the line direction biases shrinkage strains in proportion the compact dimension aspect ratios. A new algorithm that corrects this bias in strains is proposed; the direction for collapsing the column is determined by choosing a random sample face and subsequently a random point on that face as the end point for an annihilation path with equal probabilities. This algorithm is mathematically and experimentally shown to result in isotropic strains for all samples regardless of their dimensions. Finally, the microstructural evolution is shown to be similar for the new and old annihilation algorithms.
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