Exploring deformation mechanisms in a refractory high entropy alloy (MoNbTaW)

TL Dora and SK Singh and RR Mishra and H Yu and NK Rawat and A Verma, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 288, 110000 (2025).

DOI: 10.1016/j.ijmecsci.2025.110000

Understanding the deformation behaviour of refractory high-entropy alloy (rHEA) at elevated temperatures are crucial due to their potential for high-temperature applications. In this study, molecular dynamics simulations were employed using a highly accurate machine learning- based forcefield to investigate the deformation behaviour of MoNbTaW rHEA under uniaxial tensile and compressive loading. Additionally, the dependency of deformation behaviour on the applied strain rates (5e8, 1e9, 5e9 and 1e10 s_ 1) and temperatures (300, 800, 1000 and 1200 K) was investigated. The yield strength of MoNbTaW rHEA increased by two-fold during compressive loading when compared to tensile loading. During tensile deformation, the BCC-FCC-other atom transition resulted in the formation of stripe-like twinning along the 112 plane. On the contrary, during compressive loading, BCC directly transitioned into other atoms, forming twinning that later acted as the nucleation sites for dislocations. These findings further demonstrate that the deformation mechanism during tensile loading is governed by the twinning mechanism, whereas during compressive loading, dislocation- induced plasticity plays a vital role.

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