In-situ formation of Ni3Ta nanophase for strengthening tungsten alloy

Abstract

Tungsten alloys are typical tungsten-based composites that consists of tungsten particles and a matrix phase, and they have been widely used in national defense and military industries. However, the low strength of the matrix is the "Achilles’ heel" of tungsten alloys; specifically, it limits the further use of the alloys. In this work, a nano-Ni3Ta phase-reinforced ultrafine-grain tungsten alloy was fabricated via low-temperature sintering. A coherent interface with an excellent interfacial bonding strength was formed between the Ni3Ta and the matrix phase. The average grain size of the alloy was only 6.83 µm, which is significantly smaller than that of the alloy without added Ta (90 W-4.9Ni-2.1Fe-3Cu alloy, 18.06 µm) and traditional tungsten alloy (∼30 µm). The ultimate tensile strength (UTS) and total elongation (TE) of the alloy were 1139.74 MPa and 14.77 %, respectively. The excellent mechanical properties can be attributed to a synergistic effect between nanoscale Ni3Ta phase dispersion and fine-grain strengthening. These findings indicate that our approach is a novel way to develop new tungsten alloys that have high strength and toughness.