The effects of temperature on (0 0 1)<1 1 0> crack propagation in bcc iron

The results of three-dimensional molecular dynamics modeling of (0 0 1) crack nucleation and propagation in bcc iron during constant strain rate under Mode I loading are reported. The brittle crack nucleation and propagation accompanied by slip band formation is observed at temperatures [el]200 K. In contrast, above similar to 400 K the expansion of cracks is completely suppressed by transformation of slip bands into full dislocations. In the intermediate temperature range, competition between brittle crack expansion and dislocation emission is observed. The decomposition of slip bands into full dislocations is shown to be a two-stage process that involves the emission of partial dislocations from the stress concentrator.