Effect Of Metal Alloying Filler On Microstructure And Mechanical Properties Of Welded Joint During PAW Of SiCp/6061Al

Partice reinforced aluminium metal matrix composites(Al-MMCs)have many excellent properties such as high specific strength and specific stiffness,resistant wear,resistant corrosion,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.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,the form of joint surface become bad,which can easily be formed in weld metal.Especially for SiC partice reinforced Al-MMCs,the interfacial reaction between reinforcement SiCand matrix Al will occur during welding,the formation Al₄C₃ is very brittle,which will result in great decrease of welding joint performance.In order to prevent the formation of the needle-like harmful Al₄C₃ phases in the weld.In this paper 'In-situ' weld-alloying/plasma arc welding with Ar and N₂ as ionized gas,Ar as fielded gas,and Ti-Ni,Ti-Al-Ni,Ti-Ni-Si alloying as the alloying element is utilized to join the SiCp/6061A1 MMC Results show that the needle-like harmful Al₄C₃ phases are completely eliminated and a weld joint reinforced by as-rapidly solidified TiN,AlN,TiC,Ti₅Si₃,Al₃Ti phases produced by 'in-situ' weld-alloying/plasma arc welding of SiCp/6061A1 MMCs.In the test,the tensile strength of welded joint is 215.4,232.3,207.5MPa respectively when used Ti-Ni,Ti-Ni-Si,Ti-Al-Ni as alloying.the test result of mechnical property shows that the maximum tensil strength of weld joint gain,when the current is 80.In the research the welded joint making up of the Ti-Ni alloying have been heat-treated,.The test results show that the tensile strength of welded joint have increased a little after heat treatment,.according to welding organization the number of particle in the weld become more,and distributing is more equality,the tensile strength is 71 percent of matrix.