Occurrence of the Portevin Le-Châtelier effect in open-cell microcellular Al-2 wt% Mg

Abstract

Microcellular open-cell metal foams with pores of 75 or 400μm in diameter and made of pure Al or Al-2wt% Mg are tested in compression. The aluminum foam exhibits a typical smooth plastic flow and a positive strain rate sensitivity, whereas plastic instabilities and a negative strain rate sensitivity appear in the stress-strain curves of the Al-2wt% Mg foams, indicating the presence of the Portevin Le-Châtelier (PLC) effect. The effect is further confirmed by acoustic emission analysis. Taken together, the data indicate that the PLC effect is caused in this material by the sudden collective deformation of many struts across the material.