Fabrication of TiN–Ni and TiN–Co Cermets by Mechanical Milling and Subsequent Pulsed Current Sintering and Their Fracture Strength

TiN–Ni and TiN–Co cermets were fabricated by mechanical milling of TiN and Ni or Co powders, followed by pulsed current sintering. The microstructure of the TiN–Ni and TiN–Co cermet samples prepared from the non-milled powder contained a large number of pores. However, these pores were eliminated from both the sintered samples through mechanical milling of the powders. Relative densities of over 98% were achieved. Mechanical milling also improved the three-point bending strength of the cermet samples. In this study, the samples sintered from the powders milled for 28.8 ks exhibited the maximum strength, i.e., the strength of TiN–Ni and TiN–Co ceremets was 1.4 and 1.2 GPa, respectively. The fracture surface of the sample sintered from the non-milled powders was intergranular whereas that of the sample sintered from the milled powder was both intergranular and transgranular in nature.