Welding aluminium alloys to copper - by coating copper joint surface with silver and using friction welding

摘要

In welding Al alloys to Cu the surface of the Cu which will form a joint surface is coated with an intermediate layer of silver (alloy) and the joint is then made by friction welding. The intermediate layer may consist of an Ag solder applied by melting or obtd. by electrolytic deposition and in either case the layer is pref. =50 mu thick to prevent it being rubbed off during the friction welding process. The mechanical strength of the welded joint is similar to the strength of the Al alloy being welded; Al alloys and Ag doe not form the brittle intermetallic cpds. or mixed crystals that occur between Cu and Al. Despite the relatively high degree of deformation which occurs during friction welding, the silver layer remains intact, and microscopic examination of a polished longitudinal section through the weld shows no bonding defects between the Cu and the Ag and only very slight defects between the Ag and the Al.