Deformation-induced martensitic transformation kinetics in TRIP-assisted steels and high-entropy alloys

In this study, the sigmoidal kinetics of deformation-induced martensitic transformation (DIMT) in the transformation-induced plasticity (TRIP)-assisted alloys, including metastable high-entropy alloys (HEAs), austenitic stainless steels, and advanced high-strength steels (AHSSs) such as low-alloyed TRIP steels, mediumMn steels, and quenching and partitioning steels, were studied using various models. To tune mechanical stability, the influences of stacking fault energy (SFE), chemical composition, austenite grain size, deformation temperature, strain rate, and stress state were considered. The novel Fe47Co30Cr10Ni5V8-xSix (x = 3, 4, and 6 at. %) alloys were the main investigated HEAs in the present work, in which silicon addition effectively led to lowering SFE and faster DIMT kinetics by promoting the formation of body-centered cubic alpha"-martensite. The Olson-Cohen, Guimaraes (based on Johnson-Mehl-Avrami-Kolmogorov analysis), Shin, and Ahmedabadi models were analyzed and critically discussed. Moreover, a Hill-based sigmoid model was formulated as f alpha' / fsat = 1 - p / (p + epsilon q) with the parameters p and q characterizing the stability of austenite, and fsat representing the saturated volume fraction of alpha"-martensite. It was demonstrated that chi = p x q can be considered the sole austenite stability parameter. It was concluded that the proposed Hill-based model, demonstrating the highest accuracy among the studied models, can effectively simulate the kinetics of alpha"-martensite formation.