Acoustic emissions analysis of damage in amorphous and crystalline metal foams

Acoustic emission methods are used to investigate the nature and evolution of microfracture damage during uniaxial compression of ductile amorphous and brittle crystalline metal foams made from a commercial Zr-based bulk metallic glass, and to compare this behavior against that of aluminum-based foam of similar structure. For the amorphous foam, acoustic activity reveals evolution of the damage process from diffuse to localized damage through the foam stress plateau region, and reversion back towards diffuse damage in the foam densification region. Accommodation of microfracture by surrounding ductile struts, and significant point contact formation, permit high average compressive strains of ca. 80% in the amorphous foam without macroscopic failure.