Influence of titanium carbide and titanium diboride on microstructure and mechanical properties of laser metal deposition nickel‐titanium alloys

Nickel‐titanium alloys are produced via laser metal deposition using titanium carbide and titanium diboride as nucleating agents to refine the grain structure. The optimal process parameters are determined by analyzing the quality of the alloy formation. X‐ray diffraction confirms the simultaneous presence of the B19′ martensitic phase and B2 austenitic phase in the nickel‐titanium alloy fabricated by laser metal deposition. Tensile testing is performed on the samples at room temperature. The results show that adding mass fractions 0.9 % titanium carbide and titanium diboride effectively refines the grain size of the nickel‐titanium alloy fabricated by laser metal deposition, leading to improved tensile properties. Specifically, the addition increases the tensile strength by 40 % and 70 %, and the elongation by 50 % and 60 %.