Relationship between grain boundary segregation and grain boundary diffusion in Cu-Ag alloys
Relationship between grain boundary segregation and grain boundary diffusion in Cu-Ag alloys
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DOI：
10.1103/physrevmaterials.4.073403
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发表时间：
2020-06
期刊：
影响因子：
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通讯作者：
Raj Kiran Koju;Y. Mishin
中科院分区：
文献类型：
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作者：
Raj Kiran Koju;Y. Mishin
虽然已知合金成分会向晶界偏析，并且晶界中的原子迁移率大大超过晶格中的原子迁移率，但对晶界偏析对晶界扩散的影响知之甚少。原子计算机模拟通过计算合金组分的GB扩散系数作为其分离量的函数，提供了一种深入了解偏析-扩散关系的方法。在这种模拟中，采用半正则蒙特卡罗方法制备了热力学平衡的GB偏析，然后用分子动力学方法计算了所有合金组分的扩散系数。作为示范，所提出的方法应用于GB是Cu-Ag体系。所获得的GB扩散系数表现出重要的组分依赖性，这可以通过位点阻塞、位点竞争和由于预熔效应引起的GB无序来解释。
While it is known that alloy components can segregate to grain boundaries (GBs), and that the atomic mobility in GBs greatly exceeds the atomic mobility in the lattice, little is known about the effect of GB segregation on GB diffusion. Atomistic computer simulations offer a means of gaining insights into the segregation-diffusion relationship by computing the GB diffusion coefficients of the alloy components as a function of their segregated amounts. In such simulations, thermodynamically equilibrium GB segregation is prepared by a semi-grand canonical Monte Carlo method, followed by calculation of the diffusion coefficients of all alloy components by molecular dynamics. As a demonstration, the proposed methodology is applied to a GB is the Cu-Ag system. The GB diffusivities obtained exhibit non-trivial composition dependencies that can be explained by site blocking, site competition, and the onset of GB disordering due to the premelting effect.