Research On Welding Technology And Mechanism Of Particulate Reinforced Aluminium Metal Matrix Composites

Particulate reinforced aluminium metal matrix composites(Al-MMCs) have many excellent properties such as high specific strength and specific stiffness, resistant wear, resistant corrosion, resistant radiation, steady dimensions, etc.. They will increasingly be used in many fields such as aeronautics and astronautics, weapon, automobile and electron and so on, which makes 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 lead to poor weldability of Al-MMCs. When the general fusion welding technology is used in welding these materials, the form of joint surface become bad and defaults of porosity, inclusion and micro-crack, etc. can easily be formed in weld metal. Especially for SiC particulate reinforced Al-MMCs, the interfacial reaction between reinforcement SiC and matrix Al will occur during welding, the formation Al4C3 is very brittle which will result in great decrease of performance and toughness of welding joint.Aiming at the feature of Al-MMCs welding processing, the problems of Al-MMCs welding are fully summarized in this paper. Particulate reinforced Al-MMCs (Al₂O₃p/6061Al and SiCp/2124Al, etc.) taken as the object of study, the weldability of pulsed TIG (Tungsten Inert Gas) welding particulate reinforced Al-MMCs and furnace brazing Al₂O₃p/6061Al protected by argon is researched systematically. By using different filler metals and optimizing the welding processing parameters, consequently, based on optical microscope observation of weld joint, scanning electric microscope(SEM) analysis of tensile crack section, and X-ray diffraction(XRD) analysis of the phase structure of joint, the forming mechanism of welding joint and the ways on how to improve the quality of welding joint are discussed in detail.This paper puts forward that the alloying filler metal is added to weld metal in the course of pulsed TIG, the interfacial reaction between reinforcement SiC and matrix Al can be controlled to a great extent through induced reaction of alloying element Ti,...