Microstructure and mechanical properties of spark plasma-sintered La2O3dispersion-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. La(2)O(3)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 La(2)O(3)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% La(2)O(3)addition to W-7Ni-3Fe. The lowest grain size of 7.89 mu m was observed for 1.00 wt% La(2)O(3)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 La(2)O(3)in the alloy matrix. Fractography of the sintered alloy samples revealed W-W intergranular fracture.