Tungsten and Tungsten Alloys

Abstract

Tungsten is a silvery‐gray metallic element. It was first discovered in 1775 and as a metal in 1783. Metallic tungsten was first produced by the carbon reduction of tungstic acid and was termed wolfram. Tungsten is now the name used, but the chemical symbol remains as W. Tungsten has a very low vapor pressure, the highest melting point of any metal, and the highest tensile strength of any metal above 1650 degrees C. Tungsten occurs in a number of mineral forms, the most important are scheelite and wolframite. The benefication and hydrometallurgy are described along with the principal intermediate compounds used to make the metal powder. The highest reserves of tungsten are found in China. The instability of the market and economic conditions favor recycling of the metal. Tungsten's main use is in production of cemented carbides for cutting and wear resistant materials. It is also used to produce alloys for applications requiring high density such as eleclrodes, filaments and wires, and in other electronic components and in the manufacture of superalloys.

A Product‐Level Approach to Historical Material Flow Analysis

“…The finished product trade analysis for both models began with an account of products containing tungsten and processes utilizing tungsten products (e.g., metal cutting) that drew from many diverse sources, including encyclopedia references (Penrice 2001; Lassner and Schubert 2002), textbooks (Yih and Wang 1979; Lassner and Schubert 1999), proceedings from the International Tungsten Industry Association symposia, Roskill Reports (Roskill 1990), USBM and USGS publications (USBM 1980; Smith 1994), and an industry report (Burrows 1971). After this was accomplished, U.S. Census Bureau (USCB) import and export statistics were used to estimate U.S. finished product trade of these products (USCB 1975–2005, 1975–1977, 1978–2005), except in the case of aircraft and aircraft engines, for which data from USCB Current Industrial Reports (USCB 1975 to 2000) were used (see supplementary table S1 on the Web).…”

The effect of fine W particles in matrix phase on mechanical properties of tungsten heavy alloys

“…The presence of Coin W-Ni-Fe alloys has resulted in enhanced mechanical properties primarily because of two reasons: 1) increased solubility of W in the matrix phase leading to solid solution strengthening and 2) increased wettability of the liquid phase (matrix) during sintering resulting in reduced W-W contiguity (Spencer et al, 1992). Later generation of heavy alloys has completely substituted Fe with Co resulting in ternary W-Ni-Co alloys (Stuitje et al, 1995).…”