Investigation on microstructure, mechanical properties and fracture mechanism of Mg/Al laminated composites

Abstract

Herein, the Al/Mg laminated composites were successfully prepared by powder metallurgy-roll bonding, and the effect of annealing time on the microstructure and mechanical properties was studied, and the tensile and shear fracture mechanisms were revealed. The results show that, a diffusion layer with three-layer structure was formed at the Al/Mg interface during the annealing process at 300°C, which were consisted by Mg32Al47Cu7, Al3Mg2 and Al12Mg17 phases. After annealing for 60 min, the ultimate tensile strength and interfacial shear strength of the sample reached the best, with average values of 262.98±6.18 MPa and 27.83±1.59 MPa, respectively. The specimen presented multi-step fracture characteristics during tensile process, i.e., the diffusion layer with hard and brittle interface cracked locally first, and then the Mg matrix fractured, and finally the Al matrix fractured. During the shear test, the fracture position was between Al3Mg2 phase layer and Mg32Al47Cu7 phase layer, which was characterized by brittle cleavage fracture.