Microstructure and Transformation Behavior of in-situ Shape Memory Alloys by Selective Laser Melting Ti-Ni Mixed Powder
Résumé
The selective laser melting (SLM) of Ti-Ni mixed powder with atomic ratio of 1:1 was performed in the present work in order to elaborate shape memory alloy (SMA). The martensite phase of Ti-Ni alloy can be found by X-ray diffraction (XRD) analysis under temperature field, moreover, the Ti2Ni phase at a high scanning velocity. The crystalline phase images also show that the synthesized Ti-Ni alloy possessed a refined martensite microstructure. In order to evaluate the mechanical properties, the microhardness and porosity were measured. The microhardness is relatively high about 400HV(0.2) with champ temperature. Besides, the porosity is quite low due to the excellent laser energy absorptivity and meltability of Ni element. The differential scanning calorimetry (DSC) analysis shows that the transformation temperature from austenite phase to martensite phase is relatively high and stable.