Selective laser melted high Ni content TiNi alloy with superior superelasticity and hardwearing

TiNi alloys with high content Ni (52–55 at.%) are perfectly suitable for preparing wear- and corrosion-resistant parts that service on the space station, spacecraft, and submarine, because of their superior superelasticity, high strength, and hardwearing. However, the fabrication of complicated Ni-rich TiNi parts by the traditional machining method often faces problems of poor precision, low efficiency, and high cost. In this work, we succeed in preparing an excellent Ti₄₇Ni₅₃ alloy by selective laser melting (SLM), and thus, open a new way for the efficient and precise formation of complicated Ni-rich TiNi parts with superelasticity and hardwearing. An optimized processing window for compact parts without defects is reported. The elaborately fabricated Ti₄₇Ni₅₃ alloy exhibited a breaking strain of 11%, a breaking stress of 2.0 GPa, a superelastic strain of 9%, and a better hardwearing than that of casting and quenched Ti₄₇Ni₅₃ alloy. Besides, the microstructure, phase transformation, and deformation, as well as their influence mechanisms are investigated by in situ transmission electron microscope (TEM) and high-energy X-ray diffraction (HE-XRD). The results obtained are of significance for both fundamental research and technological applications of SLM-fabricated high Ni content TiNi alloys.