On the competition between nucleation and thickening in deformation twinning of face-centered cubic metals

M Daly and A Kumar and CV Singh and G Hibbard, INTERNATIONAL JOURNAL OF PLASTICITY, 130, 102702 (2020).

DOI: 10.1016/j.ijplas.2020.102702

The process of deformation twinning significantly influences the flow behavior of metals through its signature features - plasticity accommodation via twinning shear and crystal segmentation from the creation of twin boundaries. While the competition between deformation twinning and dislocation slip can be understood from fundamental physical metallurgy parameters, the link between intrinsic material properties and the evolution of deformation twin microstructures has yet to emerge. Here, we report a general methodology to evaluate the competition between nucleation and thickening of deformation twins in face-centered cubic metals. Our approach leverages the critical energies of the generalized stacking fault landscape to simulate deformation twin evolution using the kinetic Monte Carlo method. Differences in twinning behaviors are found to be intimately related to the relevant deformation process barriers of each material. Inspired by the underlying deformation kinetics, an analytical model is developed to predict the evolution of deformation twin microstructures, which provides a scalable framework for investigations of crystal segmentation. From this model, a new criterion based on intrinsic material parameters is derived to distinguish between nucleation-favored and thickening-favored deformation twinning regimes. This criterion provides new understanding of twin evolution pathways, which operate as a sub-branch under the traditional categories of deformation twinning and dislocation slip. This analysis also finds direct applications in crystal plasticity models, where first-principles estimators for dynamic microstructure segmentation are beneficial to predictive accuracy and removing reliance on phenomenological observations.

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