Effect of NiAl₃on mechanical properties and sintering of (W ₅Ti)C hard materials

Co or Ni was added to cemented (W,Ti)C as a binder for forming composite structures. The high cost of Co or Ni and the low corrosion resistance of (W,Ti)C-Co or (W,Ti)C-Ni cermet have generated interest in recent years in the search to find alternative binder phases. It has been reported that aluminides have a higher oxidation resistance, a higher hardness and are cheaper materials than Co and Ni. Using a pulsed current activated sintering (PCAS) method, the densification of (W, Ti)C and (W,Ti)C-NiAb hard materials were accomplished within 3 minutes. The advantage of this process is not only rapid densification to near theoretical density but also the prohibition of grain growth in nano-structured materials. Highly dense (W,Ti)C and (W,Ti)C-NiAl₃ with a relative density of up to 99% were obtained within 3 minutes by PCAS under a pressure of 80 MPa. The average grain sizes of the (W,Ti)C was lower than 100 nm. The hardness and fracture toughness of the dense (W,Ti)C and (W,Ti)C-NiAl3 produced by PCAS were also investigated.