Atomistic simulations of twin boundary effect on the crack growth behaviour in BCC Fe

TL;DR

This study uses molecular dynamics simulations to examine how twin boundaries influence crack growth and plastic deformation in single crystal BCC Fe, revealing increased crack resistance with more twin boundaries.

Contribution

It introduces the effect of multiple twin boundaries on crack growth behavior in BCC Fe, highlighting enhanced plasticity and crack resistance.

Findings

Twin boundaries induce plastic deformation at crack tips.

More twin boundaries lead to higher crack resistance.

A relationship exists between crack growth rate and flow stress.

Abstract

In this paper, the effect of twin boundaries on the crack growth behaviour of single crystal BCC Fe has been investigated using molecular dynamics simulations. The growth of an atomically sharp crack with an orientation of (111)$<$110$>$ (crack plane/crack front) has been studied under mode-I loading at constant strain rate. In order to study the influence of twin boundaries on the crack growth behaviour, single and multiple twin boundaries were introduced perpendicular to crack growth direction. The results indicate that the (111)$<$110$>$ crack in single crystal BCC Fe grows in brittle manner. However, following the introduction of twin boundaries, a noticeable plastic deformation has been observed at the crack tip. Further, increasing the number of twin boundaries increased the amount of plastic deformation leading to better crack resistance and high failure strains. Finally, an interesting relationship has been observed between the crack growth rate and flow stress.