Performance of powder-injection-molded W-4.9Ni-2.1Fe components

A 93 wt% W heavy alloy was injection molded into standard tensile test specimens and kinetic energy penetrators. Due to the relatively high activation energy of flow (124 kJ/mol), the rheological behavior of the molten feedstock was very susceptible to temperature variation. Using die sets with constant-volume die cavities, the tensile test specimens could be formed within a wide working window, whereas the penetrator could not be molded without defects because of different jetting phenomena during molding. The penetrator could be molded successfully using a die set whose die cavity progressively expanded during molding. The parts thus formed could subsequently be processed into intact components with full density and low carbon contents (<100 ppm). Their mechanical properties were comparable to or better than those of conventionally processed tungsten heavy alloys. Additional penetration test results indicated that powder injection molding was a viable route for processing high-performance tungsten heavy alloys.