Effect of sintering parameters on the densification and hardness of NiAl-CNTs composite

Nickel aluminides have attracted considerable interest in the past few decades owing to its unique properties. In this work, nickel aluminide (NiAl) was formed in-situ during spark plasma sintering of admixed powders of nickel, aluminium and carbon nanotubes (CNTs) after ball milling. 1 wt % CNTs was incorporated into the intermetallic matrix and the effect of varying sintering parameters investigated, particularly the sintering temperature and pressure. Results showed that a combination of higher sintering temperature with lower pressure yielded better results than lower sintering temperature and higher pressure. Thus the former parameters yielded better densification and subsequently higher micro hardness values of the NiAl-CNTs composites as compared to the latter.