Molecular dynamics simulation of strengthening dependence on precipitate Cr composition in Fe-15at.%Cr alloy

SA Ibrahim and QY Wang and Y Zhang and M Ado and GD Chung and MM Azeem, MICRON, 131, 102823 (2020).

DOI: 10.1016/j.micron.2020.102823

Molecular Dynamics simulation was employed to study precipitate composition dependence on strengthening. Edge dislocation interaction with pure, 80at.%,, and 60at.% Cr precipitates of different sizes in a matrix of Fe15-at.%Cr was investigated. The precipitates were found to be relatively hard. This is evident from the absence of shearing mechanism after the dislocation has bypassed them, the formation of an Orowan-like dislocation shape, and comparatively higher stress values. Precipitates with higher Cr content were found to greatly impede dislocation glide as indicated by the time taken by the dislocation to bypass them. The composition dependence on critical unpinning stress was also observed. The interaction of edge dislocation with precipitates having higher Cr composition leads to higher critical unpinning stress. The extent of critical unpinning stress dependence on precipitate composition is, however, not as high as was reported previously. Besides, the study has also confirmed the fact that alpha' precipitation results in the hardening of high Cr ferritic/martensitic steels.

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