Additive manufacturing of hard and crack-freeTiC-based cermets

Additive manufacturing of hard TiC-based cermets typically employs a high-energy beam as the energy source but suffers from high residual stress and microcracks. Herein, we propose an economical additive-manufacturing process for TiC-based cermets using powder extrusion printing (PEP) combined with pressureless sintering, which overcomes inadequacies such as extensive residual stress and microcracks. Complex cermet parts with high densities are successfully fabricated, thereby experimentally demonstrating the feasibility of this method. The as-produced TiC₆₀(Ni₈₈Fe₁₂)₄₀ composites exhibit a typical core-rim structure, which plays an important role in improving the interfacial bonding ability. The sintering temperature has a significant impact on the microstructure and mechanical properties. The flexural strength and microhardness increase first and then decrease at temperatures ranging from 1390 to 1430 °C. Optimum mechanical properties are achieved at 1410 °C with flexural strength and microhardness of 1013 ± 17 MPa and 965 ± 18 HV_0.2, respectively. The additive-manufactured cermets exhibit superior abrasive resistance and the main abrasive mechanism is adhesive wear accompanied by oxidative wear. The good wear resistance is attributed to the high hardness of the TiC phase and the lubricating effect of the abrasive debris.