Self-interstitial defects in hexagonal close packed metals revisited: Evidence for low-symmetry configurations in Ti, Zr, and Hf

摘要: In addition to the eight conventional high-symmetry configurations for self-interstitials in hexagonal close packed (hcp) structure, we show that four other configurations, obtained by breaking symmetry of some original ones, may be low-energy local minima or saddle points. The first two, BC${}^{\ensuremath{'}}$ and C${}^{\ensuremath{'}}$, consist basal crowdion buckled perpendicular their axes pyramidal plane, respectively. two others, PS P2S, are rotating $c$-axis split dumbbell prismatic plane second type, Using first-principles density functional theory calculations BC${}^{\ensuremath{'}}$, within 0.4 eV lowest-energy BO, Ti, Zr, Hf. could even configuration hcp-Zr its possible reorientation mechanisms compatible with internal friction measurements at variance structures. C${}^{\ensuremath{'}}$ exhibit a helicoidal easy glide motion dumbbell-crowdion type direction. These therefore constitute an important element take into account when predicting microstructural evolution zirconium-based materials under irradiation.