Effect of Fe Addition to Binder Phase on Mechanical Properties of Tungsten Heavy Alloy

In the present work, tungsten heavy alloys (WHA) in two different compositions (92 wt% W–2:1 wt% Ni/Co and 92 wt% W–2:1:1 wt% Ni/Co/Fe) were synthesized through liquid phase sintering followed by swaging and thermal treatment. Microstructure and mechanical properties were analyzed to study the effect of the binder composition on the WHA. The W–Ni–Co alloy has lower matrix volume fraction, finer tungsten particle size and low contiguity when matched to the W–Ni–Co–Fe alloy. Mechanical investigations such as tensile, Charpy and hardness were tested and were correlated with the microstructural features. W–Ni–Co alloy showed higher strength, hardness and impact due to more solubility of tungsten in the binder and low contiguity. Hence, Fe addition to binder has resulted in degradation in required properties. For further enhancement in strength, aging has been carried out at 500 °C for 1 h and improved strength is obtained at the marginal expense of ductility. W–Ni–Co alloy has a much higher Charpy impact value of 127 J when compared to alloy with Fe addition (55 J) due to lower dissolution of tungsten into the binder matrix.