Microstructures, mechanical properties and cytotoxicity of NiTiCu shape memory alloy by selective laser melting

To enhance the mechanical performance of selective laser melting (SLM) fabricated NiTi alloys and broaden their potential for biomedical applications, this study employed pre-alloyed NiTiCu powder (Ni:Ti:Cu = 45:50:5, at.%) to fabricate components via SLM. The effects of processing parameters on relative density, mechanical properties, and microstructural evolution were systematically investigated, and cytotoxicity was further evaluated. The results show that the relative density exhibits a rise–fall trend with increasing laser power, reaching about 99.8% at approximately 120 W. The optimum parameter set for overall mechanical performance was identified as 110 W and 900 mm·s -1 , yielding a three-point bending strength of 1979 MPa with a strain of 8.67%, and a tensile strength of 371 MPa with an elongation of 5.2%. X-ray diffraction analysis revealed that the SLM-fabricated NiTiCu alloy is predominantly composed of the B2 austenite phase with a minor NiTi 0.8 Cu 0.2 phase (and partial B19′ martensite); a moderate energy input was found to refine the microstructure and improve the strength–ductility synergy. Cytotoxicity tests satisfied the “non-cytotoxic” criterion specified in ISO 10993-5. Overall, by optimizing SLM processing parameters, a NiTiCu alloy with high densification, well-balanced strength and toughness, and favorable biocompatibility can be achieved, providing a sound basis for integrated structure–function biomedical applications.