Atomic-scale calculations indicate that both stress effects and chemical binding contribute to the redistribution of solute in the presence of vacancy clusters in magnesium alloys, leading to solute segregation driven by thermodynamics. As the size of the vacancy cluster increases, chemical binding becomes more important relative to stress. These solute–vacancy interactions also impact the diffusivity of vacancies and vacancy clusters in a solid solution. Simulations show that solute atoms accelerate mono-vacancy diffusion but decelerate the diffusion of vacancy clusters. As a result, solute atoms facilitate clustering and stabilize the resulting vacancy clusters, increasing their potential to promote solute segregation and to serve as heterogeneous nucleation sites during precipitation. Experimental observation of solute segregation in simultaneously deformed and aged Mg–Al alloys provides support for this mechanism.

原子尺度计算表明，在镁合金中存在空位簇的情况下，应力效应和化学结合都会导致溶质的重新分布，从而导致热力学驱动的溶质偏析。随着空位簇大小的增加，化学结合相对于应力变得更加重要。这些溶质-空位相互作用也会影响固溶体中空位和空位簇的扩散率。模拟显示溶质原子加速单空位扩散但减慢空位团的扩散。结果，溶质原子促进了聚集并稳定了所产生的空位团簇，增加了它们促进溶质分离并在沉淀过程中充当异质成核位点的潜力。