Microstructure and mechanical properties of TiC reinforced TZM composites prepared by spark plasma sintering

In this paper, TiC (1 wt%, 5 wt%, 10 wt%, 15 wt%)-reinforced TZM composites with high relative density and good mechanical properties were prepared by high energy ball milling and spark plasma sintering. The microstructure, element distribution, and phase composition of TZM-TiC composites were systematically analyzed and characterized. The mechanical properties of TZM-TiC composites were evaluated by microhardness test, room temperature compression test and high temperature compression test. The results proved that with the increase of TiC content, the size of Mo grains in TZM-TiC composites was significantly inhibited, and the morphology of the reinforcement phase changed from a spherical shape to a long stripe shape. Mo was found to be partially amorphous in TZM-TiC composites, and various second phases (TiC, Ti and Mo2C) were found in the TZM-TiC composites. Through two-dimensional mismatch theory and first-principle calculations, the strengthening effect of Mo-Mo2C interface was much higher than that of Mo-TiC and MoTi interface. The generation of amorphous Mo, the grain refinement and the second phase strengthening together significantly improve the micro-Vickers hardness and compressive strength of TZM-(10%, 15%)TiC composites, which contributes to the Vickers hardness of TZM-15%TiC reaching 885.77 HV, and the compressive yield strength of TZM-10%TiC composite reaching 2169.7 MPa. Besides, the TZM-10%TiC composite exhibits excellent thermal stability, and its compressive yield strength at 600 °C reaches 1880.7 MPa.