Microstructure and mechanical properties of spark plasma-sintered La2O3 dispersion-strengthened W–Ni–Fe alloy

An investigation of lanthanum oxide (La2O3) addition to tungsten heavy alloy (WHA) with a ternary composition of W–7Ni–3Fe was reported in this study. The mixed powders were sintered using spark plasma sintering (SPS) technique. La2O3 was added in increments of 0.25 wt%, 0.50 wt%, 0.75 wt% and 1.00 wt% to WHA, respectively. The sintered samples were characterized for microstructural evolution and mechanical properties. The influences of La2O3 addition on density, grain size, hardness, ultimate tensile strength (UTS) and ductility on W–7Ni–3Fe system were discussed in this study. The highest relative sintered density of 87.95% was obtained for 0.25 wt% La2O3 addition to W–7Ni–3Fe. The lowest grain size of 7.89 μm was observed for 1.00 wt% La2O3 addition. Similarly, the highest hardness and UTS of HV 533 and 1110 MPa, respectively, were also obtained for the same composition. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) of the samples revealed homogenous distribution of La2O3 in the alloy matrix. Fractography of the sintered alloy samples revealed W–W intergranular fracture.