Intermetallics formed at interface of ultrafine grained Al/Mg bi-layered disks by high pressure torsion at room temperature

摘要

Mg/Al bi-layered disks are fabricated by high pressure torsion (HPT) at room temperature. A thin layer of intermetallic of 0.26 micrometer in thickness forms at the interface of Mg/Al disks, which is identified as ?-Mg17Al12. This is very different to the interface of Mg/Al produced by other techniques such as diffusion bonding and friction stir welding where both ?-Mg17Al12 and ?-Al3Mg2 form and the ?-Al3Mg2 layer is much thicker than the ?-Mg17Al12 layer. This unusual phenomenon is attributed to the interfacial energies of formation and the effect of room temperature HPT on diffusion of Al in Mg and the ?-Mg17Al12 layer.