Effect of WC Addition on Phase Formation and Microstructure of TiC-Ni Composites

Abstract

In this research, titanium carbide-nickel (TiC-Ni) composites, with tungsten carbide addition, were fabricated by using a powder metallurgy technique. The TiC-Ni mixtures containing between 0-15 wt. % tungsten carbide (WC), were compacted and then sintered at 1300°C and 1400°C, respectively. The phase formation and microstructure of the WC-added TiC-Ni composites have been investigated by X-ray diffraction and scanning electron microscopy techniques. Mechanical properties of these composites were assessed by an indentation technique. The X-ray diffraction patterns showed no evidence of tungsten rich phases in the sintered WC-added cermets. This indicates that during the sintering process, tungsten carbide particles were dissolved in metallic binder phase (Ni phase) via dissolution/re-precipitation process during liquid phase sintering. The liquid phase formed during sintering process could improve sinterability of TiC-based cermets i.e., it could lower sintering temperatures. The TiC-Ni composites typically exhibited a core-rim structure. The cores consisted of undissolved TiC particles enveloped by rims of (Ti, W)C solid solution phase. Hardness of TiC-Ni composites increased with WC content. Sintering temperature also had a slight effect on hardness values.