LIQUID PHASE SINTERING OF SUB MICRON WC COMPOSITES CONTAINING NEW BINDERS BASED ON BORON DOPED ALUMINIDES

Densification behavior of sub micron tungsten carbide composites based on boron doped Fe₆₀Al₄₀ and Ni₃Al binders were investigated. Soft cobalt binder phase in WC hard metals was replaced by harder and tougher Fe₆₀Al₄₀ and Ni₃Al intermetallics with boron level up to 0.1wt%. Intermetallic binders were prepared in ultrafine form under controlled atmosphere using ring grinding, blended with sub micron WC powder and then uniaxilly hot pressed under 20 MPa pressure in argon atmosphere for 4 minutes duration at temperatures of 1450 °C, 1500 °C and 1550 °C. It was found that the density of composites increased significantly and WC grain size increased slightly with increase in sintering temperature. The composites exhibited highest density (about 99.5 %TD) and minimal grain growth in WC at sintering temperature of 1500 °C. The presence of boron was found to facilitate densification during liquid phase sintering and boron also resulted in achieving uniform microstructure with continuous binder phase, nearly full density and high faceted features in the structure.