Atomistic simulation of shear deformation at bcc-Fe grain boundary and precipitation strengthening by Cr23C6
K Nakamura and T Kumagai and T Ohnuma, MATERIALS TODAY COMMUNICATIONS, 33, 104711 (2022).
We investigate the temperature and the tilt angle dependence of the shear deformation behavior at a body centered cubic (bcc)-Fe grain boundary (GB) by utilizing classical molecular dynamics simulations. We found that the shear deformation at a 001 axial bcc-Fe GB accommodates GB migration. The critical shear stress needed to induce GB migration was found to decrease with an increase in the temperature or molecular dynamics simulation time, because GB migration is a thermally activated process. The tilt angle dependence of the critical shear stress is successfully explained by the presence of a specific structure unit composed of under-coordinated atoms. It was suggested that Cr23C6 precipitation within the bcc-Fe crystal decreases the critical stress required to generate dislocations, because of the interface between the precipitation and parent phases. On the other hand, Cr23C6 precipitation on a 001 axial bcc-Fe GB was found to increase the critical shear stress, while the precipitation didn't change the shear deformation mechanism. The degree of strengthening was verified by theoretical equation to evaluate the shear strengthening by the ordered precipitates.
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