Research On The Welding Of In-Situ TiB₂/Al Composites

Aluminium matrix composites, which have many excellent properties such as high specific strength and specific stiffness, resistant corrosion, resistant radiation, low thermal expansion coefficient, steady dimensions, will be widely used in many fields such as spaceflight, aeronautics, weapon, autocar, electronics industry and sports industry and so on, and make them become one of the main topics of research and development in the field of metal matrix composites. However, the distinct parameters of thermal physical properties such as melting point, thermal conductivity and thermal coefficient of expansion between reinforcement and matrix, which lead to the poor weldability and the difficulty in obtaining high strength welded joint, severely hinder the application of the composites in welded construction. Therefore, a systematic study on the weldability of aluminium metal matrix composites is imminnent.In this paper, aiming at the feature of aluminum matrix composites welding processing, in-situ TiB2/Al composites as a test object were welded by TIG welding and vacuum liquid diffusion welding without interlayer,and we have got high-quality welded joints, a systematic study on weldability and magnesium for aluminum matrix composite's melt welding and diffusion welding. Mechanical properties of welded joints were measured by tensile, and the microstructure and change of compositions of welded joints of composites were observed by scanning electron microscopy and X-ray diffraction.In-situ TiB2/Al composites were welded by pulse TIG welding with parent metal filler in Ar-He. Results showed that the protective effect using Ar-He is better than using Ar, and the main parameters that affected the properties of joints are the ratio of He in Ar-He mixed gas, the flow of gas, pulse peak current, pulse frequency, welding current. It was found that pulse is the important factors, and pulse frequency is the most important factor. We can get high-quality and high-strength TIG welding joints when these factors have a bast match. The vacuum liquid diffusion welding without interlayer for in-situ TiB2/Al composites was investigated. It was found that when the certain amount of liquid phase alloy appears, with effect of certain welding pressure, the interface of composites are joined perfectly. And the main parameters that affected the properties of joints are the surface state, welding temperature,welding pressure,welding time, and the welding temperature is the most important factor. We can get high-quality and high-strength diffusion welding joints when these factors have a bast match.