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,hard-ness,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 μtm 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.