Plastic deformation behavior of Pd-based binary alloys: A first-principles study

Abstract

The generalized stacking fault energy is a critical parameter for plastic deformation and phase transition behavior of alloys. Here, the generalized stacking fault energies of palladium-based binary alloys (Pd 1− x M x , M = Mo, W, Re, Ru, Os, Rh, Ir, Pt; x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) in face-centered cubic (fcc) phase are systematically investigated by combining the coherent potential approximation with the exact muffin-tin orbital method within the framework of density functional theory. Analysis of the plastic behavior of Pd 1− x M x reveals that Mo, W, Re, Ru, and Os alloying elements can promote twinning, which in turn can be used to strengthen Pd alloys. When alloying reaches up to 30 at.% Mo, 40 at.% W, or 40 at.% Re, phase transition from fcc to hexagonal compact packing and stacking faults are the primary deformation of Pd 1− x M x . Contrarily, Rh, Ir, and Pt significantly suppress the twinning ability, and full slip becomes the dominant deformation mechanism. Such distinct deformation behavior of Pd-based alloys is attributed to their electron redistribution upon alloying, owing to the d - d hybridization between alloy elements and Pd atoms. This study gives valuable insight into the phase stability and provides useful guide for the design of high-strength alloys. • Alloying rich Mo, W, and Re into Pd promotes the phase transition from fcc to hcp. • Alloying elements Mo, W, Re, Ru, and Os can promote twinning mechanism of Pd 1−x M x . • Rh, Ir, and Pt alloying with Pd would facilitate full slip deformation. • Deformation of Pd 1−x M x is related to d-d hybridization between alloy atoms and Pd.