Effect of boron on the microstructure of spark plasma sintered Ultrafine WC

► Influence of boron on the coarsening of WC is studied by interrupted sintering. ► At low temperatures, boron oxide produces rough solid-liquid interface. ► At high temperatures, boron acts as a coarsening medium. ► Inclusion of boron produces isotropic coarsening in WC. ► Sintering atmosphere and boron concentration control size and shape of grains in WC-B.