Abstract:Microstructure and interfacial structure of laser-brazed joint between TiNi shape memory alloy (SMA) and stainless steel (SS) were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The brazing seam primarily consists of α-Ag solid solution, α′-Cu solid solution and eutectic structures. Three continuous reaction layers form between the silver-based filler metal and SS during laser brazing and are austenite (A), martensite (M), A + M and α-Ag + α′-Cu + M, respectively. The reaction layer between the filler metal and TiNi SMA is mainly composed of Ti(Ni, Cu) and (Ni, Cu)Ti2 compounds.

Key words: TiNi shape memory alloy; stainless steel; laser brazing; interfacial structure