Interfacial characteristic of multi-pass caliber-rolled Mg/Al compound castings

Abstract

Herein, magnesium/aluminum (Mg/Al) composite rods were prepared by compound casting and multi-pass warm caliber rolling, and the effect of caliber rolling on the evolution of the interfacial microstructure and mechanical properties of the Mg/Al compound castings was investigated. The results reveal a uniform interface, which can be divided into three layers consisting of Al3Mg2, Al12Mg17 and (Al12Mg17 + Mg) eutectic structure, was formed during the compound casting. Afterwards, the brittle reaction layer fragmented during the rolling process, and was effectively eliminated after 12 passes. Meanwhile, the fresh Al and Mg bases squeezed out and bonded together under the rolling force. The interface formed after the final rolling process had no visible intermetallic compounds. Further, an inhomogeneous deformation in the Mg and Al bases was observed during the rolling process. Initially, the Al clad layer accommodated a larger proportion of the plastic deformation. With increasing number of passes, however, the strain in the Mg core layer increased and, after 12 passes, the deformation of both layers tended to be equivalent. The strength of the Mg/Al composite rod increased gradually and the ultimate tensile stress reached a value of 247 MPa after 12 passes.