Atomistic modeling of nanosized Cr precipitate contribution to hardening in an Fe–Cr alloy

Molecular dynamics simulations of the interaction between an edge dislocation and nanosized Cr precipitates in bcc Fe have been performed to investigate the hardening effect of α′ phases in high Cr ferritic/martensitic steels. The critical resolved shear stress needed for an edge dislocation to overcome Cr precipitates of diameter between 3 and 6 nm is larger than for dislocation glide in the bcc Fe lattice containing 10% Cr solute atoms. This indicates that the precipitation of α′ phases leads to hardening in high Cr ferritic/martensitic steels. The MD simulations reveal that the interspacing of Cr precipitates plays a more crucial role in the hardening of Fe–Cr alloys than the precipitate size. An attractive interaction exists between an edge dislocation and nanosized Cr precipitates, which is evident as a decrease in total energy when an edge dislocation is placed within in a Cr precipitate.