The nucleation mechanism of martensite and its interaction with dislocation dipoles in dual-phase high-entropy alloys

P Wang and ZC Song and YC Lin and QQ Li and HT Wang, JOURNAL OF ALLOYS AND COMPOUNDS, 909, 164685 (2022).

DOI: 10.1016/j.jallcom.2022.164685

The recent progresses in experiments have proven that the recently synthesized dual-phase high-entropy alloys (DP-HEAs) exhibit ultrahigh ductility without sacrificing the high strengthen. However, the original atomic mechanisms of the martensitic transformation process and its interaction with dislocations remain mysterious. In this work, the nucleation mechanisms of martensite are thoroughly investigated with various arrangement of dislocation dipoles via molecular dynamics (MD) simulations. Both stress-induced and thermal-induced martensitic transformation are reproduced in our simulations, which obeys the Burgers orientation relationship. Under the thermal fluctuation, the nucleation of martensite is controlled by the localized stress levels and strain energies. The thermal-induced martensite is found to nucleate near the dislocation dipoles once the strain energy reaches the required value. Upon loading, the fast-moving stress induced martensite bends and wraps the dislocation dipoles in propagation path. These results provide a fundamental understanding of the martensitic nucleation in DP-HEA and its strengthening and toughening mechanisms, contributing benefits to design new alloys. (c) 2022 Elsevier B.V. All rights reserved.

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