Structural Changes and Stability Switching by Indentation Simulation in Amorphous Metals

Abstract

We have attempted to reveal the deformation mechanism of amorphous metals by local lattice instability analysis, based on the positive definiteness of the atomic elastic stiffness coefficients, B_ij^α. In our previous study, changes in inhomogeneous structure are explained by the observation of the stability-switching or transition between detB_ij^α > 0 and detB_ij^α < 0. In this study, we have performed the indentation simulation on a binary amorphous metal, and discussed the inelastic deformation in the amorphous metal by Voronoi polyhedra analysis and the stability-switching of local lattice instability. The indentation simulation predicts that rearrangements of atoms occur not only on structures below the indentation point but also inside the amorphous metal structure. These structural changes produce a significant volume change in the Voronoi polyhedra, the stability-switching based on local lattice instability analysis, and a local volume reduction evaluated within scales of a few hundred atoms.