This paper aims to better control the mechanical properties and functional properties of NiTi alloy.
NiTi alloy samples with equal atomic ratio were formed by selective laser melting (SLM). X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy and tensile testing methods were used to study the effects of different laser power and scanning speed on the densification behavior, phase transformation characteristics and mechanical properties of NiTi alloy.
Compared with the laser power, the variation of the keyhole effect caused by the change of scanning speed is more intense, which has a greater effect on the densification behavior of SLM NiTi alloy. The effect of the laser power on the phase transition temperature is small. The increase of scanning speed weakens the burning degree of Ni element, so phase transition temperature decreases. The results of DSC test and tensile test show that the scanning velocity can significantly change the phase transition temperature, martensite twins reorientation and stress–strain behavior of SLM NiTi alloy.
This study provides a potential method to regulate the mechanical properties and functional properties of NiTi shape memory alloy in the future and NiTi alloys formed by SLM with good elongation were obtained because the Supercellular crystal structure formed during the nonequilibrium solidification of SLM and the superfine precipitates dispersed in the alloy prevented the dislocation formation.
The authors gratefully appreciate the financial support from Key-Area Research and Development Program of Guangdong Province, No. 2020B090923001, National Natural Science Foundation of China (U2001218,51875215,81772428), Guangdong Province Special Support Plan for High-Level Talents (2019TQ05Z110), the Fundamental Research Funds for the Central Universities (2019MS060), Key Project of Regional Joint Foundation of Guangdong Province (2020B1515120013) and Capital’s Funds for Health Improvement and Research (CFH 2020–2-5131).
Song, C., Huang, J., Liu, L., Hu, Z., Yang, Y., Wang, D. and Yang, C. (2022), "Study on phase transformation behavior and mechanical properties of equiatomic ratio NiTi alloy formed by selective laser melting", Rapid Prototyping Journal, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/RPJ-05-2021-0114
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