Influence of Niobium Content on The Microstructure and Properties of W–Nb/TiC Composites Prepared by Conventional Sintering
W–Nb/TiC composites were prepared by mechanical milling and conventional sintering. Field-emission scanning electron microscopy, high-resolution transmission electron microscopy, microhardness, and Charpy impact test analyses were used to characterize the samples. Results showed that W–1wt%Nb/TiC exhibited the maximum relative density (94%) and impact energy (116 KJ/m2) and that (Nb, Ti) C solid solution and Nb2C formed in the W–Nb/TiC composites. However, the density and impact energy decreased when the Nb content exceeded 1 wt% because the second-phase particles agglomerated at the grain boundaries (GBs) with increased Nb content. This agglomeration caused stress concentration of the GBs, which easily initiated cracks. The microhardness did not change significantly with the increased Nb content of the W–Nb/TiC composites.