Laser engineered net shaping in-situ synthesis of NiTi alloy: Effects of processing parameters

Nickel-Titanium (NiTi) alloy is difficult to be machined and fabricated due to its properties of rapid work-hardening and superelasticity. Traditional manufacturing methods, such as casting, vacuum arc melting, and hot-isostatic pressing, have disadvantages of high cost, time-consuming, and limitation in the complexity of parts’ fabrication. In order to reduce or solve these problems, laser additive manufacturing methods have been studied in the fabrication of NiTi alloy. Among the investigations, laser engineered net-shaping (LENS) in-situ synthesis of NiTi from blended Ni and Ti powders shows its unique advantage of cost-effectiveness and flexibility in tailoring NiTi’s phase transformation properties. In addition, it is reported that LENS in-situ synthesized NiTi parts have comparable properties with NiTi alloys fabricated from pre-alloyed powders. However, there are no existing investigations on the effects of processing parameters on the mechanical properties of the LENS in-situ fabricated NiTi parts. The processing parameters would have great influences on the properties of the LENS in-situ synthesized NiTi parts. This paper, for the first time, reports the effects of laser power, powder feeding rate, and Z increment of the deposition head on microstructure, microhardness, and Young’s modulus of the LENS in-situ synthesized NiTi parts.