Texture, aging, and superelasticity of selective laser melting fabricated Ni-rich NiTi alloys

This work studies the impact of selective laser melting (SLM) fabrication on the microstructure and texture of Ni-rich NiTi alloy. SLM NiTi samples were fabricated with a high laser power of 250 W and 1.25 m/s scanning speed. A comprehensive aging study of as-fabricated alloys is also presented to reveal the effects of aging time and temperature on transformation behavior. The shape memory properties were investigated by shape memory effect and superelasticity experiments. It was found that although SLM fabricated samples show lower strength than the initial ingot, their sharp [001] texture along the building direction improve their superelastic response substantially. In addition, it was shown that transformation temperatures can be tailored and upon thermal treatments of 350 °C-1 h and 600 °C-1.5 h, superelastic recovery up to about 5.5% can be obtained at body and room temperatures which make these alloys very promising for potential biomedical applications.