Tungsten heavy alloy: Nano-crystallinity and alloying induced low temperature sintering, microstructure and mechanical properties

In this study, a tungsten heavy alloy with a composition of 90 W-4.9Ni-2.1Fe-3.0Cu was processed using powder metallurgy. Pure elements were ball-milled to develop a mechanically alloyed nano-grained solid solution to reduce the required sintering temperature. The alloy was then liquid-phase sintered in a hydrogenated argon atmosphere at 1250 °C. Microstructural characterization revealed that the high-energy ball milling process successfully developed a tungsten solid solution with a reduced tungsten grain size to a level of 15 nm, facilitating effective low-temperature (i.e., 1250 °C) liquid-phase sintering with 88% relative density. The tungsten grains grew mostly in a polygonal shape, coalesced to a large size, and had strong interfacial integrity with the nickel‑iron‑copper matrix. Mechanical properties characterization revealed a significantly high microhardness level of 380 HV, compressive yield strength of 910 MPa, and ultimate compressive strength of 1326 MPa. The applied compressive stress induced intergranular crack propagation leading to the fracture of the sample with a failure strain of 25.6%. •90W-4.9Ni-2.1Fe-3.0Cu sintered (with 88% relative density) at a low temperature (1250°C) using liquid phase sintering process.•High-energy ball milling to nano-structured single-phase crystal and low melting point copper attributed to low temperature sintering.•Sintered tungsten grains were coalesced mostly to polygonal shape with strong interfacial integrity with nickel-iron-copper matrix.•Sintered alloy possessed high hardness (380 HV), compressive yield (910 MPa) and ultimate (1326 MPa) strength and ductility (25.6%).