Liquid Phase Sintering of WC-FeAl and WC-Ni_3Al Composites with and without Boron

摘要

Intermetallic matrix composites, WC-FeAl and WC Ni_3Al, based on 40 vol% intermetallic binder, were prepared from ultrafine precursor powders and processed by liquid phase sintering. Intermetallic binders, Fe_(60)Al_(40)-500ppm B, Ni_3Al-500ppm B and Ni_3Al were prepared in ultrafine form by controlled atmosphere ring grinding, blended with submicron WC powder and then uniaxially hot pressed under constant load at 1450, 1500 and 1550 °C. The composites exhibited near full density at the highest sintering temperature. It was found that composites containing Ni_3Al-based binder had the same or lower than those composites which contained FeAl-based binder but Ni_3Al based composites exhibited higher toughness. It seems that the higher hardnesses in FeAl-based composites could be associated with the higher hardness of the binder phase. The addition of 500 ppm B to Ni_3Al was found to significantly inhibit WC grain growth after uniaxial hot pressing but the precise mechanism of this effect is yet to be investigated.