Fabrication and Characterization of Tungsten Heavy Alloys with High W Content by Powder Metallurgy

In order to fabricate high-performance tungsten heavy alloys (97W–2.1Ni–0.9Fe (wt pct) and 99W–0.7Ni–0.3Fe) with higher W content and density by powder metallurgy technique, the ultrafine composite powder was synthesized through two-step reduction approach and used as the raw materials. Contrary to the expectations, it was found that a small amount of Ni has a great effect in activated pre-sintering, resulting in an undesired grain growth of W to micron size. Therefore, another simple and efficient method was developed to prepare high-purity, ultrafine and high-W-content composite powders. The sintering densification behavior of the prepared composite powders, as well as mechanical properties and corrosion resistance of as-sintered alloys were systematically investigated. The bending strength, compression strength, hardness, fracture toughness and anti-corrosion property of obtained 97W–2.1Ni–0.9Fe alloys are better than those of 99W–0.7Ni–0.3Fe alloys, attributed to the more homogeneous microstructure comprised of finer W grain and larger volume fraction of matrix phase.