Effect of initial surface roughness and thickness of inserted Cu on Al bonding in air

摘要

Al bonding in air can be carried out with the liquefaction by the reaction diffusion with Cu insert metal at the temperature range between melting temperature of Al and eutectic point of Al-Cu system. Al bonding in air depends on micro deformation of each bonding surface which causes the fracture of Al oxide film. Effect of the initial surface roughness and the thickness of insert metal which may affect micro deformation was investigated in this study. Each experiment was carried out at bonding temperature of 893K and bonding pressure of 1MPa. Surface roughness was an important factor at the experimental condition of thin insert metal. Surface roughness may change local pressure of micro projection on the bonding surface. However, effect of the surface roughness weakens gradually with the increasing of thickness of insert metal. Thickening of insert meal may obtain an ability of micro deformation. Two peaks were confirmed on the tensile stress-holding time curves. This behavior related with the transitional change of microstructure in bond until isothermal solidification like the liquid diffusion bonding.