時効硬化合金中のG.P.ゾーン形成の駆動力に関する原子論的解析

抄録

Nanosized precipitates of solute atoms called Guinier-Preston (G.P.) zones are known to play a significant role in the precipitation-hardening effect on the Al alloys. In this study, the effects of temperature and vacancy concentration on the formation of G.P. zones were investigated using the atomistic approach based on density functional theory (DFT). An on-lattice potential model for a dilute Al-Cu-vacancy system was constructed using the DFT-calculated energies for the pairs and triplets of Cu atoms and vacancies in the Al matrix, and then applied to atomistic kinetic Monte Carlo calculations. As a result, the planar segregation of Cu atoms along the {100} planes was successfully reproduced at finite temperatures. It was confirmed that the formation of G.P. zones was accelerated with increasing temperature and vacancy concentration via the activated vacancy-assisted mechanism for exchanges of pairs of atoms.