Lightweight TiC based cermet fabricated by a pre-solid phase sintering-assisted pressureless infiltration process

Abstract

This paper introduces a novel process, known as pre-solid phase sintering-assisted pressureless infiltration (PSPS-PI), aimed at addressing issues related to the segregation of hard particles and excessive porosity in the manufacturing of lightweight cermet based on TiC. The PSPS-PI process involves compressing a green TiC powder compact with a minor Ni powder addition, followed by vacuum-based solid-phase sintering to create a fully consolidated TiC preform. This study explores the influence of TiC particle size and Ni content on the microstructure and properties of TiC–Cu composites, conducting a comparison with direct pressureless infiltration (D-PI). The results indicate that the high-melting-point Ni element promotes the formation of sintering necks between TiC and Ni, aiding in the consolidation of TiC particles. The stable skeleton ensures that TiC particles remain in their initial positions during subsequent pressureless infiltration, effectively preventing TiC powder segregation. TiC and Ni create a dissolutive wetting system during pressureless infiltration. The formation of the Ni2SnTi intermetallic compound significantly enhances the wettability with Cu alloy, leading to a reduction in porosity and the occurrence of crack defects within the composite. As particle size decreases, the preform's porosity decreases, resulting in a reduced proportion of soft metal binder and lower residual stress. Consequently, finer TiC powder leads to improved cermet hardness and a reduction in the number of micro-crack defects. In general, PSPS-PI allows for the attainment of low porosity, a uniform microstructure, enhanced hardness, and outstanding wear resistance in the lightweight cermet based on TiC with the appropriate TiC particle size (D50 = 10.2 μm), achieving a remarkable hardness of 642.9 (Hv30) and excellent toughness.