Landolt-Börnstein - Group VIII Advanced Materials and Technologies

12 Refractory metals

Abstract

Refractory metals and their alloys are used in a wide variety of products and branches comprising electrical and electronic devices, light sources, medical equipment, automobiles, aerospace and defence, chemical and pharmaceutical industry or premium and sporting goods. Commercial applications of refractory metals and alloys by industry are listed. Refractory metals are extracted from ore concentrates, processed into intermediate chemicals, and then reduced to metals. The widely applied reducing agent for the production of Molybdenum (Mo) and Tungsten (W) is hydrogen, for Tantalum (Ta) sodium and for Niobium (Nb) aluminum. Compaction of refractory metal powder is accomplished by die pressing and cold isostatic pressing. Data of commercially applied refractory metal powders relevant for the compacting process together with the compacting pressure as applied in large-scale production and the resulting fractional densities are provided. The compactability of molybdenum is compared with that of powders possessing a lower yield strength, such as nickel, iron and aluminum, The compactability of AKS tungsten, tantalum and pure tungsten is illustrated. The effect of the green density on the sintering behavior of molybdenum powder of various powder sizes is described, followed by the illustration of influence of the powder particle size on the sintering behavior of tungsten. The atomic, structural, electrical, and thermophysical properties of refractory metals are listed. Typical recrystallization temperature and ultimate tensile strength at T = 1000 °C of commercial molybdenum and tungsten based rod material with defined amount of deformation are tabulated.

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Title
12 Refractory metals
Book Title
Powder Metallurgy Data. Refractory, Hard and Intermetallic Materials
Book DOI
10.1007/b83029
Chapter DOI
10.1007/10858641_2
Part of
Landolt-Börnstein - Group VIII Advanced Materials and Technologies
Volume
2A2
Editors
  • P. Beiss
  • R. Ruthardt
  • H. Warlimont
  • Authors
  • G. Leichtfried
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