Production and characterization of TZM based TiC or ZrC reinforced composites prepared by spark plasma sintering (SPS)

TZM alloy (molybdenum alloy containing 0.5–0.8 wt% titanium, 0.08–0.1 wt% zirconium and 0.016–0.02 wt% carbon) provides an advantage at elevated temperatures compared to pure molybdenum due to having a superior recrystallization temperature by the formation of TiC and ZrC in the molybdenum matrix. In this study, besides the formation of carbides, TiC and ZrC were directly added into TZM powder and their effects were investigated. The aim of this research is to design a composite material which has better densification behavior with improved mechanical properties. Additional TiC and ZrC could provide a grain refinement and inhibition the beginning of recrystallization temperature. In this study, TZM-TiC and TZM-ZrC composites with varying amounts of TiC and ZrC (0-20 vol%) as an additives were sintered by spark plasma sintering (SPS). The characterization of the prepared composites were carried out in terms of their densification, microstructure and mechanical properties such as microhardness and fracture toughness. Weight reduction of TZM was achieved and the lowest densities have been measured as 8.95 g/cm³ for TZM-20 vol%TiC sample and 9.34 g/cm³ for TZM-20 vol%ZrC. Grain size decreased with the addition of carbides to 6.5 μm for TZM-20 vol%TiC and 6.6 μm for TZM-20 vol%ZrC composites. According to Vickers microhardness test, the highest values were measured as 4.10 GPa for TZM-20 vol%TiC and 3.88 GPa for TZM-20 vol%ZrC.