The effects of SiC addition on the sintering densification, phases, microstructure and mechanical properties of W

Refractory tungsten(W) materials are widely used in high-temperature field due to their high melting point. But there are some problems with W, such as low strength and poor toughness. The grain boundaries are very sensitive to impurities, which is one of the most important reasons for the degradation of tungsten properties. In this paper, we use silicon carbide (SiC) as a deoxidizer, which is designed to react with the oxygen atoms in tungsten at high temperature to purify and strengthen the grain boundaries. The effects of SiC addition on the sintering densification, microstructure and mechanical properties of W were investigated. Results show that SiO2 and W2C are produced by the interface reaction between SiC and W, which reduces the free energy of sintering system and promotes the densification process, the maximum relative density reaches 99.4%. When SiC content is 1 wt%, compared to pure tungsten, the tensile strength significantly increases from 220 MPa to 431 MPa, the hardness increases up to 697.13 HV. Furthermore, the fracture mode of this W is mainly transgranular fracture, which is due to interface reaction strengthening and purification grain boundary strengthening.