Laser autogenous brazing – A new method for joining dissimilar metals

Abstract

The joining of dissimilar metals is a critical process for the future development and evolution of medical devices which would enable the selective use of the unique properties exhibited by biocompatible materials such as stainless steel and titanium, as well as shape memory materials such as NiTi to locally tailor the properties of implantable medical devices. Many joints between dissimilar metals, however, suffer from significant intermetallic formation which causes them to fail in a brittle manner. This study investigates a novel process, laser autogenous brazing, being developed by the authors that enables joining of dissimilar metal pairs through a braze-like interface without the use of filler materials to maintain biocompatibility while forming a robust mechanical joint. The formation of brittle intermetallics is mitigated by controlling the thermal profile in the irradiated material through the use of thermal accumulation to limit melting to the joint interface. The strength, composition, microstructure, and fracture surface morphologies of the resultant joints are investigated as a function of processing parameters and thermal simulations are used to aid in understanding the joint formation mechanism.The joining of dissimilar metals is a critical process for the future development and evolution of medical devices which would enable the selective use of the unique properties exhibited by biocompatible materials such as stainless steel and titanium, as well as shape memory materials such as NiTi to locally tailor the properties of implantable medical devices. Many joints between dissimilar metals, however, suffer from significant intermetallic formation which causes them to fail in a brittle manner. This study investigates a novel process, laser autogenous brazing, being developed by the authors that enables joining of dissimilar metal pairs through a braze-like interface without the use of filler materials to maintain biocompatibility while forming a robust mechanical joint. The formation of brittle intermetallics is mitigated by controlling the thermal profile in the irradiated material through the use of thermal accumulation to limit melting to the joint interface. The strength, composition, microstr...