Effect of alloying elements on elastic properties, generalized stacking fault energy, and critical resolved shear stress of Pd metal: A first principle study

Abstract

Functional alloying elements (B, Si, P, Ti, V, Zn, Ga, In and Sn) and impurity elements (H and O) have an impact on the mechanical performance complexly. In order to clarify the effect of those elements, the elastic properties, generalized stacking fault energies and critical resolved shear stress of the Pd-X alloys were comprehensively analyzed by first-principle method. The variation of those elastic and ductile properties via alloying elements has been obtained. Crystal chemical analysis shows that the ionic bond between Pd and O determines the stability of O occupying tetrahedral site. Meanwhile, the energy barrier and dislocation distribution analysis support that the perfect dislocation will be decomposed to partial dislocations during the critical slip. According to electronic structure analysis, the increase of ductility (i.e., the decrease of unstable stacking fault energy along 112¯ directions) is attributed to the decrease of charge density on the slip surface. Moreover, a criterion, called misfit ratio R = |εs/εb|, is introduced to clarify major contribution of solid solution strengthening ΔτCRSS/c2/3 is lattice distortion effect or GSFE change effect caused by alloying elements.