Electro-mechanical coupling in FCC metal rhodium from first-principles simulations

Abstract

Electroplasticity in metals has been controversial since it is extremely hard to decouple the electron-induced heating in experiment. To illustrate the origin of this phenomenon, we applied density-functional theory (DFT) calculations to examine the response of injecting electrons and holes to face-centered-cubic metal, Rh, under finite shear deformation. We firstly examine the single crystal and find that single-crystal Rh can become more ductile/stronger with the electron/hole injection due to the less/more charge distribution between the sheared bonds cross the slip plane under deformation. Then the nanoscale twins are introduced to illustrate microstructure effect, and the simulation results indicated that nanoscale twins weaken the Rh, leading to a softening effect. With injected electron/hole, the nanotwinned structure displays the same more ductile/stronger effects as the single-crystal Rh. The origin of these effects arises from the weakened/enhanced bonding along twin boundaries. This study provides some insights on the origin of electroplasticity in metals.