Effects of ThO2 on the solid-state sintering behavior of W–Ni–Fe alloy

Dilatometric analyses were employed to investigate the influence of ThO2 particles on the sintering behavior of W–Ni–Fe alloys up to 1450 °C which is below the liquid formation temperature. The activation energies were obtained by analyzing by the shift of the iso-density points as a function of the linear-heating rate. It is well known that the dominant sintering mechanism of tungsten particles is grain-boundary diffusion in the solid-state. The activation energies were 304.00–467.39 kJ/mol for W–Ni–Fe and 519.10–2949.60 kJ/mol for the thoria doped alloy, respectively. The results for the non-added alloy are in agreement with the values reported in the literature. The possibility that the much higher energies for the doped alloy reflect a retardation of sintering due to the presence of thoria particles at the surface of the tungsten is discussed.