First-principles calculations of twin-boundary energies in face-centered-cubic metals

Abstract

Nanotwin strengthening mechanism has been successfully applied to a variety of metallic materials. The strengthening originates from the hindering effect of twin-boundary (TB) on dislocations, and the formation of twin is greatly determined by the magnitude of the TB energy (TBE). In this work, the TBEs of three face-centered-cubic (FCC) metals were calculated by first-principles, the effect of the supercell size (the TB spacing and TB area) on the TBE was investigated, and the relationship between the TBE and the twinning formation mechanism was discussed. The results show that the TBEs calculated in this paper are in good agreement with the experimental values. Meanwhile, the magnitude of the TBE explains reasonably the twinning formation ability of these FCC metals in experiments.