LASER AUTOGENOUS BRAZING – A NEW METHOD FOR JOINING DISSIMILAR METALS

摘要

The joining of dissimilar metals is a critical process forrnthe future development and evolution of medicalrndevices which would enable the selective use of thernunique properties exhibited by biocompatible materialsrnsuch as stainless steel and titanium, as well as shapernmemory materials such as NiTi to locally tailor thernproperties of implantable medical devices. Many jointsrnbetween dissimilar metals, however, suffer fromrnsignificant intermetallic formation which causes themrnto fail in a brittle manner. This study investigates arnnovel process, laser autogenous brazing, beingrndeveloped by the authors that enables joining ofrndissimilar metal pairs through a braze-like interfacernwithout the use of filler materials to maintainrnbiocompatibility while forming a robust mechanicalrnjoint. The formation of brittle intermetallics isrnmitigated by controlling the thermal profile in thernirradiated material through the use of thermalrnaccumulation to limit melting to the joint interface.rnThe strength, composition, microstructure, and fracturernsurface morphologies of the resultant joints arerninvestigated as a function of processing parameters andrnthermal simulations are used to aid in understandingrnthe joint formation mechanism.