Fabrication of ultrafine-grain and great-performance W–Ni–Fe alloy with medium W content

Abstract

The tungsten alloy with medium W content (wt.%) is a combination of high strength and high toughness, which has wide potential applications in related fields. In order to fabricate high-performance W–Ni–Fe alloy with medium W content, ultrafine tungsten powder obtained by sol-spray drying-hydrogen reduction method was employed as raw material. The medium W content W–Ni–Fe alloys with different compositions were systematically studied for the first time, i.e., 50W–25Ni–25Fe, 50W–35Ni–15Fe, 70W–15Ni–15Fe and 70W–21Ni–9Fe. The results show that the mechanical properties of medium W content W–Ni–Fe alloys prepared by this method are excellent, the highest tensile strength is 945 MPa, the highest elongation is 31.7%. The tensile strength, density and elongation of tungsten alloy with Ni/Fe ratio of 7:3 are better than those of tungsten alloy with Ni/Fe ratio of 1:1 when W content is fixed. With the same Ni/Fe ratio, the density of tungsten alloy with 50W series is higher than that of tungsten alloy with 70W series, but the tensile strength is lower. The microstructure of tungsten alloys with four components are uniform and fine, the grain size of tungsten is just 3–5 μm. The two main fracture modes of samples are the cleavage fracture of tungsten grains and the dimple fracture between tungsten grains and γ phase.