Nanoscale deformation mechanisms in CrCoNi medium entropy alloys: Influence of crystallographic orientation and chemical short-range order

C Matlock and N Zhang, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, 114, 105762 (2025).

DOI: 10.1016/j.euromechsol.2025.105762

This study investigates the effect of crystallographic orientation and chemical short-range order (CSRO) on the mechanical properties and deformation mechanisms of single-crystalline CrCoNi medium entropy alloys (MEAs) through atomistic simulations under uniaxial tension. The results reveal that mechanical properties are highly sensitive to crystallographic orientation. The 111-oriented model demonstrates the highest stiffness, strength, and toughness, while the 100 orientation exhibits the lowest. In contrast, the 110 model shows the lowest yield stress but benefits from significant toughening due to deformation twinning (DT). The deformation mechanisms are found to vary with orientation: DT dominates in the 110 model, while partial dislocation glide primarily governs the 111 and 112 cases. The presence of CSRO enhances all mechanical properties studied and modifies deformation pathways. In the 110 orientation, CSRO alters twin nucleation, favoring their formation within multilayer stacking faults (MSFs) over intrinsic stacking faults (ISFs). For the 111 orientation, CSRO promotes DT while delaying MSF formation to higher strains, enhancing toughness. These findings highlight the complex interplay between crystallographic orientation and CSRO in shaping the mechanical behavior of CrCoNi MEAs.

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