Strain-Mediated Defect Engineering toward Rapid Atomic Migration in Fe–Al Diffusion Couples
Zhijie Ding, Peng Li, Zhiwei Qin, Weiben Huang, Peng Zhao, Dianwu Zhou, Xiangchen Meng, Yutaka S. Sato, Honggang Dong
Abstract
In the pursuit of rapid atomic migration in lightweight Fe–Al diffusion couples, rationally designing short-circuit diffusion paths has become paramount. Herein, a strain-mediated defect engineering strategy was proposed for reducing the vacancy activation energy and enhancing diffusion behaviors along dislocations (DLs) and grain boundaries (GBs). Combining the modified Arrhenius-type relationship, an interfacial apparent activation energy of 139 kJ mol –1 was acquired utilizing defect engineering, which was decreased by about 49%. This was closely related to high-density vacancies, DLs, and GBs formed in strained Fe and Al materials, which provided more low activation energy paths for atomic migration. First-principles calculations indicated that the lattice diffusion barrier mediated by monovacancy was reduced with strain incorporation, attributed to the weakened atom–vacancy bond as a consequence of less electron transport. The synergistic effect of abnormal electron-charge distribution in the bulk and strong attraction force at the Al/Fe interface radically resulted in rapid atomic migration, collectively regulating the “breaking–forming bond” process.