Preparation of multi-walled carbon nanotube-reinforced TiNi matrix composites from elemental powders by spark plasma sintering

Carbon nanotube (CNT)-reinforced TiNi matrix composites were synthesized by spark plasma sintering (SPS) employing elemental powders. The phase structure, morphology and transformation behaviors were studied. It was found that thermoelastic martensitic transformation behaviors could be observed from the samples sintered above 800 °C even with a short sintering time (5 min), and the transformation temperatures gradually increased with increasing sintering temperature because of more Ti-rich TiNi phase formation. Although decreasing the sintering temperature and time to 700 °C and 5 min could not protect defective MWCNTs from reacting with Ti, still-perfect MWCNTs remained in the specimens sintered at 900 °C. This method is expected to supply a basis for preparing CNT-reinforced TiNi composites.