Ultra-High Hardness TiC-W-Ni Cermets Prepared by Spark Plasma Sintering of Ultra-Fine TiC Powder

Abstract

High-performance TiC-W-Ni cermets were fabricated employing Ni powder, self-synthesized ultra-fine TiC and W powders through spark plasma sintering. The impacts of different W and Ni contents on the microstructure and mechanical properties of TiC-W-Ni cermets were investigated. The findings indicated that all samples displayed a core-rim structure, with the dark-colored core being incompletely dissolved TiC and the rim phase consisting of (Ti, W)C solid solution. An increase in W content led to a larger fractional volume of the rim phase and finer grain size of cermet. However, agglomeration and abnormal growth of grains also increased. The cermet with a composition of TiC-10 W-20Ni achieved the highest fracture toughness of 9.51 MPa·m^1/2 and a hardness of 2014 HV₃₀. In contrast, the cermet with a composition of TiC-20 W-10Ni achieved the highest hardness value of 2257 HV₃₀ and a fracture toughness of 7.87 MPa·m^1/2. A decrease in Ni content led to a decrease in transgranular fracture and an increase in intergranular fracture, thus causing a decrease in fracture toughness. At a constant ratio of W to Ni, increasing TiC content from 70 wt% to 80 wt% reduced the quantity of grains with the core-rim construction but increased the number of abnormally grown grains, and thereby made an increase in hardness and a slight decrease in toughness.

Graphical Abstract