Deformation and fracture of an amorphous PdCuSi alloy in V-notch bending tests—I: Model mechanics of inhomogeneous plastic flow in non-strain hardening solid

Abstract

Model mechanics of the inhomogeneous plastic deformation of amorphous Pd 77.5Cu 6Si 16.5 as a non-strain hardening solid is proposed. The dependence of the yield stress on plate thickness, notch angle, and notch depth is investigated with the V-notch bending test. Plastic deformation under plane stress occurs by an antiplane strain mechanics, consistent with predictions for Dugdale's plastic zone and also contraction in the present model. In specimens under plane strain, the general yield deformation pattern shows a plastic hinge. Assuming Von Mises' criterion, a plastic constraint factor of 1.20 is calculated, in good agreement with that of Green's slip line field. The dependence of serrated flow on the extension rate was also measured over the range of 1 × 10 −4 to 1 × 10 2mm/min. Serrated flow is found to disappear at a critical extension rate ( ϵ c ). ϵ c = Aexp(− H/ kT) can be confirmed as the empirical mechanical equation of state for serrated flow. The activation energy (H) for onset of serrations is 0.35 eV.