Microtructure and Mechanical Behaviors of Electron Beam Welded Ti_(44)Ni_(47)Nb_9 Shape Memory Alloys

摘要

The microstructure, martensitic transformation behavior and mechanical properties of the Ti_(44)Ni_(47)Nb_9 electron beam welding joints were systemically studied in this research. The results showed that the microstructure of the fusion zone was composed of equiaxed grains with a small quantity of eutectic structure around the grain boundaries, and the grain size in the fusion zone was smaller than that in the as-cast microstructure. The ultimate tensile strength was a little lower than that of the base. The dissolution of niobium in the matrix obstructed the martensite transformation and decreased the martensite start temperature (M_s). After being deformed at the low temperature, the welding joints exhibited good wide transformation hysteresis, which was similar to that of the base metal.