Preparation of Ta-W-Si alloy by powder metallurgy method

The Ta-W-Si alloys were prepared by hot pressed sintering and spark plasma sintering. The microstructure and phase composition of sintered alloy were investigated by XRD (X-ray diffraction), SEM (scanning electron microscopy), BSE (backscattered electron imagine), and EDS (energy dispersive spectrum), and the influences of sintering method and silicon content by mass on densification and hardness were analyzed. The results show that, the relative density of alloy prepared by two sintering methods reaches over 96%, and the addition of silicon element is benefited to the densification of alloy. Two different regions can be found in SEM and BSE images, which are identified as Ta-W and Ta₃Si by XRD pattern. Hardness increases clearly with the addition of silicon element. The primary strengthening mechanisms are the second-phase strengthening of silicides, the grain refinement strengthening, and the oxidative concentration in grain boundary region.