Plastic Deformation Behavior of Pd-Based Binary Alloys: A First-Principles Study

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 (Pd1_xMx, 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 Pd1_xMx 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 Pd1_xMx. 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.