Microstructural evolution and metallurgic reactions in dissimilar joints of Nitinol wire and medical alloys during laser microwelding

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The manufacturing and fabrication of medical devices is a vast field in which the physical connection of devices' different parts is required to meet certain standards. This entails that they should have a pertinent level of mechanical strength and functional properties, depending on their applications. Baylis Medical Company (Baylis)'s Radio Frequency (RF) Puncture System is the world leader for creating controlled perforations in cardiac and vascular tissues and has been the world-wide gold standard or even saved countless lives through supplying innovative, safe and effective surgical devices. One of the major manufacturing challenges for this world leading technology and the devices is joining of Nitinol (NiTi) shape memory alloys to other medical alloys (e.g., stainless steel, PtIr) at a small scale. The proposed research between the University of Waterloo and Baylis is to systematically investigate the dissimilar laser microwelding of NiTi alloy to stainless steel (SS) and PtIr alloys, as well as laser microwelding enabled processing of NiTiPt high temperature shape memory wire to achieve a reliable assembly of small components for medical device applications; it will also deepen the understanding of microstructural changes and phase transformation of NiTi/SS and NiTi/PtIr joints during laser welding at a small scale in material processing, and improve the knowledge of the effects of base metal and interlayer chemical compositions, laser welding process parameters and configurations on the weld microstructure, including IMC formation, and mechanical properties. The implementation of this collaborative project will accelerate the new product design for Baylis moving from R&D laboratory to industry scale in Canada, which will keep Canada's innovation capability at the pioneer position and place Canadian businesses at the forefront of technology development in the manufacturing and medical industries.