Magnesium Alloy - Aluminum Alloy Explosion Composite Interface Structure And Properties Of The Impact Studies

As a special welding technology, explosive cladding with unique advantage is applied widely to bond the dissimilar materials, and has great developing potency. The bonding zone of the explosion composite material is different from the substrate metals in the components, structures and properties, which has its own significant and important characteristics. This paper by OM, SEM, EDS and mechanical test introduces systematically the structures and mechanical properties of the original state of magnesium alloy-aluminum alloy explosion composite material, and studies further the effect of the long-term low-temperature, short-term high-temperature heat treatment and heat deformation on the structures and the properties of the composite interface. The research shows that:AZ31/7075 explosion composite interface of the original state is waveform interface with melting block near wave ridges, and in the interface there is a tiny atomic diffusing layer which is about 0.6μm. It achieves a solid metallurgical combine, so the shear strength reaches 70.4 MPa. The fracture shows tough characteristics and fracture EDS component analysis found that the fracture on the aluminum side has 10% (wt%) Mg. So the interface is of good metallurgical combine, without obvious intermetallic compounds.For low-temperature long-term heat treatment, we should strictly control the temperature and holding time to prevent excessive diffusion of magnesium, aluminum atoms, and the formation of intermetallic compounds, thus avoiding to weakening the interface strength. Keeping temperature at 170℃for four hours can improve shear strength, and make the adiabatic shear bands on magnesium alloy side recrystallize to eliminate the source of crack.When high-temperature short time heat-treat, the intermetallic compounds near the interface thicken with the increase of temperature and extension of time. And the interface strength because of the formation of intermetallic compounds on the bonding zone declines rapidly and with the thickening intermetallic compounds, and further reduces the interface strength; the fracture is also brittle fracture characteristics. Fracture component analysis also shows that the fracture happens in the intermetallic compounds in the interface.When heat deformation, preheat will lead intermetallic compounds generated at the interface, but the larger deformation will cut off intermetallic compound, and make the substrate metal fill the fracture to achieve bonding by metal keys, and improve the interface strength and fracture showed mixed fracture with brittle fracture and partial ductile fracture.