Observation of interface of two kinds of bi-metal composite parts prepared by thixo-forging

摘要

Two kinds of bi-metal composite parts (Sn-15%Pb and Pb-22%Sn bi-metal system, and Al-7%Si and SiCp/6061 MMC bi-metal system) were prepared by the strain-induced melt activated thixo-forging.The interfaces of the bi-metal composites were observed by OM and SEM.The observations show that the semisolid metals keep independence during thixo-forging.The solid phases in the semisolid slurries maintain their original morphologies after thixo-forging.The liquid phases near the interface mix together and form a thin layer.The interfaces are bonded firmly with the metallurgical bonding.No oxide layers are found at the interfaces.Strengths of the interfaces were investigated by the micro-hardness test.The experimental results show that the composite interfaces have high strength.However, the agglomerated enhancing particles cause fine defect on the interface of the Al-7%Si and SiCp/6061 MMC bi-metal composite.