Diffusion bonding of Al alloy to Al2O3 ceramic
(National Key Laboratory of Advanced Welding Production Technology,
Harbin Institute of Technology, Harbin 150001, China)
Harbin Institute of Technology, Harbin 150001, China)
Abstract: A layer of Cu was sintered on the surface of Al2O3 ceramic before bonding, and then diffusion bonding technology was applied to bond Al2O3/Cu to Al alloy. SEM and EDS were applied to analyze the interfacial microstructures of Al2O3/Cu/Al joint. The preliminary research shows that Al/Cu interfacial microstructures are the main factor affecting joint strength. With increasing bonding temperature and time, ((Al)+θ) mixture separates out from Al alloy, and (Cu)+ γ1）mixture separates out from Cu layer. The two kinds of mixtures develop first along interface, then (Cu)+γ1) microstructure turns progressively into (ξ2 +δ) with bonding temperature and time prolonged. At the same time, ((Al)+θ) and /(ξ2 +δ) phases move gradually into base materials. The two kinds of changes result in reducing bonding strength greatly. The optimum diffusion bonding parameters are determined as follows: T=773K, t=1226s and p=6MPa, at which the tensile strength of the joint is 108MPa, and the shear strength of the joint is 45MPa.
Key words: Al alloy; Al2O3 ceramic; diffusion bonding