Modification of microstructure and performance via doping Ti in W–1TiC fine-grained alloy

Abstract

The Ti-doped TiC-dispersion-strengthened W alloys are prepared by mechanical alloying in this work. The influence of Ti content on the performance and microstructure of W–1TiC alloys is systematically investigated. Results show that the ultra-fine and homogenized W–1TiC–0.5Ti alloy powders with average size of 212.3 nm have high sintering activity. The relative density of its pressed sample sintered at 1930 °C is nearly full densification (over 99%). Introducing Ti in W–1TiC alloy forms a Ti-rich region, which inhibits the growth of the TiC and maintains the uniform distribution of the TiC, around the TiC particles in sintering. The dispersed TiC decreases the average grain size of sintered W–1TiC–0.5Ti alloy into 2.71 μm. Moreover, the W(110) and TiC(111) form semi-coherent interface at W/TiC phase boundary to modify the interface compatibility between W matrix and TiC ceramic phase. The stable semi-coherent interface strengthens the phase boundary and limits the growth of the TiC particles and W grains. Accordingly, the ultimate tensile strength and microhardness of W–1TiC–0.5Ti alloy at RT are 426 MPa and 860 ± 11 HV0.2, respectively. The improvements of W–1TiC–0.5Ti alloy in mechanical properties are attributed to the synergistic effect of fine-grained strengthening, dispersion strengthening, and interface strengthening.