Study On Clad-rolling Of Aluminum-coated Magnesium Composite Plates And The Properties Of Interface

With the development of economy,the demonding for natural resources has increasingly aggravated the shortage of them.Magnesium alloys are attracting more and more attention for their abundant reserves and advanced properties,but poor plasticity at room temperature and low corrosion resistance limit their development and extensive application in industry.However,clad-rolling maybe a good ideal to resolve the two puzzles mentioned above.In this paper,aluminum-coated magnesium composite plates were fabricated by clad-rolling,and then treated by diffusion annealing.The effects of clad-rolling temperature,clad-rolling reduction,sintering temperature,sintering time on the microstructure,element distribution and mechanical properties of the composite interface have been investigated by metallographic microscope,scanning electronic microscope,vicker's hardmeter,electronic testing machine and etc.The results show that:aluminum-coated magnesium composite plates fabricated by clad-rolling at 400℃×45%have excellent bonding properties with no intermetallic compounds on the interface.The single-pass reduction of AZ31 magnesium matrix is 45.4%by clad-rolling at 400℃×45%,and its microstructure is well-recrystallized structure,so we think clad-rolling can effectively improve the plastic deformation capacity of AZ31 magnesium.The intermetallic compounds Mg₁₇Al₁₂ are found next to the Mg side of interface,and·Al₃Mg₂ are found near the other side after diffusion annealing.When the thickness of intermetallic compounds layer is more than 5μm,the bonding strength would greatly fall down.The combine mechanism of aluminum-coated magnesium composite plates can be summarized as follows:Firstly,the surface layer of metal breakdown and a large number of new metals are squeezed out during clad-rolling with large reduction. Secondly,aplit mechanism and energy mechanism start to work,and generate a high bounding strength.Last,during diffusion annealing,the diffusion mechanism has little favourable effect on aluminum-coated magnesium composite plates.