Multiscale computational model of TWIP and TRIP in medium/high entropy alloys

YZ Liu and J Wang and SH Oh and SP Hu and W Fu and XG Song and BJ Lee, JOURNAL OF ALLOYS AND COMPOUNDS, 1022, 179770 (2025).

DOI: 10.1016/j.jallcom.2025.179770

Nickel-based medium-entropy alloys, such as Ni47Cr25Co2Mo6Fe20 (at%), have demonstrated remarkable plasticity and strength at cryogenic temperatures, outperforming their behavior at room temperature. However, a critical challenge remains a comprehensive understanding of the underlying deformation mechanisms and the influence of factors such as temperature and nanoscale precipitates. This study presents the development of a multiscale computational model for systematically investigating the mechanical properties and deformation mechanisms of medium- and high-entropy alloys (M/HEAs). A key advantage of this model is its ability to transfer computational parameters and deformation mechanisms from the atomic to the mesoscopic scale. At the atomic scale, molecular dynamics simulations are employed to analyze the temperature dependence of stacking fault energy (SFE). These effects are further examined in single-crystal nanowires and nanocrystalline models, elucidating how variations in SFE influence deformation behavior. The atomic-scale simulation results are subsequently utilized to calibrate a crystal plasticity model, ensuring a consistent representation of deformation mechanisms across different scales. The multiscale model is validated by fitting mesoscale computational parameters to stress-strain and hardening curves across a range of temperatures, demonstrating good agreement with experimental data. To further extend the applicability of the model, we investigate the effects of temperature, crystallographic texture, and nanoscale precipitates on deformation mechanisms and mechanical properties. Additionally, the contributions of twinning and stress-induced martensitic transformation to strength are quantitatively evaluated. This work establishes a robust multiscale framework for understanding the fundamental mechanisms governing strength and ductility in M/HEAs. The findings offer critical insights and practical guidelines for the advanced design and processing of M/HEAs, particularly for applications in extreme environments.

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