Study on Interface Characteristics of Al/Mg/Al Composite Plates Fabricated by Two-Pass Hot Rolling

In this study, 5052/AZ31B/5052 composite plates were fabricated by two-pass hot rolling, under the rolling parameters 623 K/15 min/40% for the first pass and 673 K/10 min/50% for the second pass. The structure and element change in the zone of the joint interface were studied by means of optical microscope (OM), scanning electron microscope (SEM), and energy diffraction spectrum (EDS). The results showed that the bonding mode of the joint interface between AZ31B and 5052 alloy was metallic bonding after the first pass hot rolling, but the bonding mode of the finished composite plate appeared the distribution characteristic alternating with metallic bonding and metallurgical bonding. Two distinct intermediate layers including Mg17Al12 and Al3Mg2 can be clearly observed in the joint interface. During the second pass hot rolling, the AZ31B and 5052 layer were elongated along the rolling direction, while the Al3Mg2 and Mg17Al12 layers were up in the joint interface. After the tensile strength testing of the composite plate, the interface bonding appeared very well without any debonding.