Quantitative Determination of the Generalized Stability of Fe-based Binary Alloys

Our recent study [Acta Mater. 201 (2020) 167–181] proposed a unified generalized stability (GS) criterion to design high-performance metallic materials, but quantitative determination the GS of plasticity deformation remains a big challenge. Here, by combination of molecular dynamics simulations with the classical dislocation thermos-kinetic theory, we reliably calculate the thermo-dynamics driving forces ΔG, kinetic energy barrier Q, and subsequently predict the GS values of Fe-based binary alloys. Our calculation shows that the GS values of pure α-Fe increase from 0 at yield point to 2.7 at uniform elongation stage, and the GS values of Fe-based alloy increased with the increase of alloy content. These results imply that for different systems large GS correspond to the thermodynamically more unstable status that is hard to sustain more dislocation evolution, i.e., low plasticity. This quantitative calculation provides a general guideline to use GS theory for further design alloys with excellent mechanical properties.