Role of short- and long-range ordering on diffusion in Ni-Al alloys
Role of short- and long-range ordering on diffusion in Ni-Al alloys
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DOI：
10.1103/physrevmaterials.3.093402
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发表时间：
2019-09
影响因子：
3.4
通讯作者：
J. Goiri;S. Kolli;Anton Van der Ven
中科院分区：
文献类型：
--
作者：
J. Goiri;S. Kolli;Anton Van der Ven
不同程度的短期和长期的秩序表现出的多组分固体复杂的第一性原理计算的非稀释扩散系数。时间和空间的变化，在当地的程度的顺序影响个别跳的迁移障碍，并可能导致连续跳，最终影响宏观输运系数之间的强相关性。在这里，我们报告的第一性原理研究扩散在富镍Ni-Al合金。我们用团簇展开哈密顿量来描述每一跳的端态能量和迁移势垒。进行动力学蒙特卡罗模拟来计算宏观输运系数。有序度的变化被证明在影响扩散系数中起着重要的作用。虽然Al在无序的富Ni fcc固溶体中具有比Ni更高的迁移率，但由于强烈的热力学趋势使Al被捕获到不连续的亚晶格位置，因此在有序的$L{1}_{2}\phantom{\rule{4pt}{0 ex}}{\ensuremath{\gamma}}^{\ensuremath{\gamma}$相中，Al的移动的明显减少。
The varying degrees of short- and long-range order exhibited by multicomponent solids complicates a first-principles calculation of nondilute diffusion coefficients. Temporal and spatial variations in the local degree of order affect the migration barriers of individual hops and can result in strong correlations between successive hops that ultimately affect macroscopic transport coefficients. Here we report on a first-principles study of diffusion in Ni-rich Ni-Al alloys. We used cluster expansion Hamiltonians to describe the energies of the end states and migration barriers of each hop. Kinetic Monte Carlo simulations were performed to calculate macroscopic transport coefficients. Variations in the degree of ordering are shown to play a significant role in affecting diffusion coefficients. While Al has a higher mobility than Ni in the disordered Ni-rich fcc solid solution, it becomes significantly less mobile in the ordered $L{1}_{2}\phantom{\rule{4pt}{0ex}}{\ensuremath{\gamma}}^{\ensuremath{'}}$ phase due to strong thermodynamic tendencies that keep Al trapped to disconnected sublattice sites.