Theoretical strength and charge redistribution of fcc Ni in tension and shear

Abstract

We employ a first-principles total-energy method to investigate the theoretical tensile andshear strengths of fcc Ni systematically. The theoretical tensile strengths are shown to be36.1, 10.5 and 34.1 GPa in the [001], [110] and [111] directions, respectively. We indicatethat [110] is the weakest direction due to the formation of an instable bct ‘phase’in the tensile process. The theoretical shear strengths are, respectively, 5.1 and15.8 GPa in the ‘easy’ and ‘hard’ directions in the slip system, and 6.4 GPa in the slip system. Both the tensile and the shear strengths are consistent with eitherexperimental or theoretical values. The different shear strengths in the ‘easy’ and ‘hard’directions originate from the different charge redistribution under the shear strain. Theshear strain along the ‘easy’ direction of [112] results in a charge distributed in the which forms a directional bond, while the strain along the ‘hard’ direction of [112] makesthe charge extend to the whole {111} interlayers.