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

摘要

TiNi alloys with high content Ni(52-55 at.%)are perfectly suitable for preparing wear-and corrosionresistant 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 Ti_(47)Ni_(53) 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 Ti_(47)Ni_(53) 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 Ti_(47)Ni_(53) 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.