Research On The Microstructure And Property Of Joining Si₃N₄/2024Al Aluminum Matrix Composite

High-volume content of ceramic reinforced aluminum matrix composites havecharacteristics of light weight, high strength, high stiffness ratio, adjustablecoefficient of thermal expansion, etc. In the light electronic packaging, thermalcontrol components and other areas have extensive application prospects. However,due to the constraints of connectivity, high-volume content of ceramic reinforcedaluminum matrix composite materials will be restricted.In this paper, three different brazes were usesd to join Si₃N₄/2024Al aluminummatrix composite between itself. Untreated Si₃N₄/2024Al aluminum matrixcomposite was welded by Sn-Zn-Ti alloy. Also, the Si₃N₄/2024Al aluminum matrixcomposite which was sputtered Al coating on the surface, was welded by Zn-Al、Al-Si-Mg alloy. While the will Si₃N₄/2024Al aluminum matrix composite, whichwas chemical nickel-plating on the surface, was welded by Sn-Ag-Cu filler. Themechanis m of joining Si₃N₄/2024Al was studied.In this paper, we find that a obvious diffusion layer was generated between theelement Sn diffused to the Si₃N₄/2024Al aluminum matrix composite and theSi₃N₄/2024Al aluminum matrix composite. The mechanism of Sn diffus ion wasanalyzed by Young’s equation and Cavity theory and we got that the vaporation ofZn in vacuum and the exist of second phase strengthening particles were necessaryto accomplish Sn diffuisive layer. Sn-Zn alloy is employed to conduct wetting testsover Si₃N₄/2024Al composite （45%Si₃N₄） in vacuum under different temperaturesand different welding time. On surface of the composite formed a thick Sn diffus ionlayer, and the the layer grows thicker as temperature increases. while diffusion is notobserved when temperature is below330℃. The microstructure and mechanicalproperties of the joint between aluminum matrix composites with a Sn diffusivelayer and Cu alloy was analyzed. The joining mechanism was also analyzed. Whenbrazing Si₃N₄/2024Al composite material with Sn-Zn-Ti filler, it can be formed veryclear diffusion layer between the filler metal and base metal due to the diffusion ofSn, obtaining shear strength11.28MPa at room temperature. Using Sn-Ag-Cu fillermetals vacuum brazing high-volume ceramic reinforced aluminum matrixcomposites whose surface deposit Cu and Ni active layer has its ideal connectionavailable with the shear strength being separately39.01MPa and45.03MPa. UsingAl-Si-Mg filler metal vacuum brazing high-volume ceramic reinforced aluminummatrix composites whose surface deposit Ti active layer, there is a obvious reaction layer between the filler metal and the base metal. Al, Si from the filler metal and Tireact Ti-Al-Si needle-like compounds, which run through the reaction layer. The Tiactive layer improves the wetting property of the braze to the base. The joint shearstrength is up to83.96MPa.