Twinning to slip transition in ultrathin BCC Fe nanowires

Abstract

We report twinning to slip transition with decreasing size and increasing temperature in ultrathin <100> BCC Fe nanowires. Molecular dynamics simulations have been performed on different nanowire size in the range 0.404-3.634 nm at temperatures ranging from 10 to 900 K. The results indicate that slip mode dominates at low sizes and high temperatures, while deformation twinning is promoted at high sizes and low temperatures. The temperature, at which the nanowires show twinning to slip transition, increases with increasing size. The different modes of deformation are also reflected appropriately in the respective stress-strain behaviour of the nanowires.

A molecular dynamics study on the mechanical properties of Fe–Ni alloy nanowires and their temperature dependence

“…34 It is reported that nanowire orientation, size, temperature and strain rate could affect the deformation mechanism of the metal nanowire. 34,35,49 Herein, according to the features, the deformation mechanisms of Ni-Fe alloy nanowires vary with the Ni concentration. The Ni-Fe alloy nanowires with a low Ni concentration (0.5 and 5.0 at%) deform mainly by twinning mechanism under tensile loading.…”

“…The result is consistent with Choudhary's report that ultrathin <100> BCC Fe NWs deform by the dislocation slip mechanism at high temperatures while twinning dominates at low temperatures. 35 The dependence of the deformation mechanism on the Ni content and temperature could be attributed to the stacking fault energy.…”

“…As in ultrathin <100> BCC Fe NWs, deformation by slip dislocation dominates at small sizes and high temperatures, while twinning is promoted at large sizes and low temperatures. 35 Zhang et al explored the inuence of a 5-fold twin boundary on the structural and mechanical properties of face center cubic (FCC) Fe NWs. 36 The higher Young's modulus and higher critical stress upon loss of elasticity were attributed to the twin boundary that suppressed the dislocation nucleation.…”