5 Micro-welding of shape-memory alloys

This chapter discusses the challenges in the joining of Nitinol (i.e. NiTi alloys) shape-memory alloys (SMAs) which are becoming increasingly popular in medical-device applications due to their unique shape-memory effect and pseudoelastic (i.e. superelastic) functional properties. The chapter starts by providing a brief introduction to the properties of SMAs followed by a review of how different micro-welding techniques affect the alloy microstructure and properties. Fundamentals for key micro-welding processes used in joining Nitinol SMAs are detailed, including resistance and laser micro-welding (i.e. RMW and LMW).