PNNL

Abstract

The self-interstitial atoms (SIAs) mediate the evolution of micro-structures which is crucial in understanding the instabilities of hexagonal close packed (HCP) structures. Taken zirconium as a prototype, we investigate the pressure effect on the stabilities of SIAs using first-principles calculations based on density-functional theory. We found that the pressure greatly affects the stability of the SIAs. The SIAs in basal planes are more stable to changes in pressure. The most stable SIA configuration changes from basal octahedral (BO) to octahedral (O) at pressure of 21 GPa. The lowest formation enthalpy configuration switches from BO to S (split-dumbbell) at P = 30 GPa. Our results reveal that it is important to take the pressure effect into account when predicting the micro-structural evolution of HCP structures.