Study On Casting Compoundtechnology And Interface Ofaluminum/Magnesium Layeredmaterial

Bimetal laminar composites are widely used in modern industries such as defense,aerospace,and automotive duo to take full advantage of the excellent properties of the two substrates.Having the advantages of high specific strength,high specific rigidity of the magnesium?Mg?alloy and excellent plasticity and corrosion resistance of the aluminum?Al?alloy,the Al/Mg layered composite material has very wide application prospect.The current methods for preparing Al/Mg layered composites include extrusion,rolling,explosive,and compound casting.The compound casting method is suitable for industrial production due to the stable quality of interface bonding and low production cost.However,when Al is in contact with Mg directly in the process of compound casting,the interface will inevitably produce brittle intermetallic compound layers,which will seriously harm the bonding properties of the composite material.In this paper,plasma spraying surface modification technology and traditional liquid-solid compound casting technology are combined to improve the interface properties of Al/Mg composite materials.Firstly,based on the study of the formation mechanism of solid phase diffusion interface and the effect of Ni interlayer on the diffusion reaction of Al/Mg,the composite ingots were prepared by casting the molten Mg into the surface of Al subsrate.The microstructures and mechanical properties of interface with different Mg pouring temperature were studied.Finally,the composite ingots were rolled,and the interface microstructure of the composites after rolling were analyzed.The deformation rules of the brittle reaction layers and the Ni intermediate layer during the rolling process were discussed.For the Al/Mg solid state diffusion interface,when the diffusion temperature is below the eutectic temperature?437??,the diffusion layers are Al₃Mg₂ and Al₁₂Mg₁₇.When the diffusion temperature is above the eutectic temperature,a new eutectic layer(Al₁₂Mg₁₇+?-Mg)is formed at the interface.As the diffusion temperature increases,the thickness of diffusion layer increases;for the Al/Ni/Mg solid state diffusion interface,when the diffusion temperature is 420?,no obvious diffusion layer is observed at the interface,and when the diffusion temperature is 440?,Mg₂Ni compound layer was found at the Mg-Ni interface,but the thickness is much smaller than that of the Al-Mg compound layers.With the introduction of nickel interlayer,the maximum shear strength at the interface of solid state diffusion increased from 3.6 MPa to 5.8 MPa.For the Al/Mg liquid-solid interface,when the casting temperature is 680?,there are obvious cracks and local reactions layers at the interface.When the casting temperature rises to 700?,the interface compound layers are divided into three layers and the crack disappears.As the pouring temperature increases,the thickness of diffusion layers increase.For the Al/Ni/Mg interface,when the casting temperature is 680?and 700?,no obvious compound layer is observed.When the casting temperature rises to 720?,the interface forms Mg₂Ni,Al₃Ni,and?Al₃Ni+?-Al?compound layers.With the introduction of the nickel interlayer,the maximum shear strength increased from 17.3 MPa to 25.4 MPa.After the composite ingot was rolled,the intermetallic compound layers and Ni interlayer were broken and refined under the action of rolling force.The broken intermetallic compounds are squeezed into the two sides of the matrix under the action of the rolling force to achieve bonding,and after the annealing treatment,the micro-cracks and holes in the local area of the interface disappear..