Deformation-free nanotwin formation in zirconium and titanium

摘要

An irradiation-induced nanotwinning mechanism in zirconium and titanium is proposed, based on molecular dynamics simulations. Atomistic configurations before and after nanotwinning are characterized in Zr, Mg and Ti, using four different semi-empirical potentials. An elliptical self-interstitial cluster is identified as the precursor to nanotwinning. These elliptical self-interstitial clusters spontaneously formed and transformed into nanotwins in two cases-Zr and Ti-but not in Mg. The nanotwins are crystallographically equivalent to {11 (2) over bar1} (11 (2) over bar(6) over bar) tensile deformation twins, which are experimentally observed in Zr and Ti. We noted that nanotwins appeared in the hcp materials with low {10 (1) over bar0} prismatic plane stacking fault energy (SFE), relative to their basal extrinsic SFE. (C) 2019 Elsevier B.V. All rights reserved.