refractorymetalle

Refractory metals are a group of metallic elements known for their extremely high melting points, good high-temperature strength, and structural stability. The most commonly identified members are tungsten, molybdenum, niobium, tantalum, and rhenium. Some classifications also include hafnium and zirconium due to their high melting points, though their chemical behavior and oxidation resistance differ from the core group.

These metals exhibit high density and a high elastic modulus, giving them stiffness and strength at elevated temperatures. They often retain mechanical integrity under extreme heat, but pure forms can be brittle and difficult to work with. Many refractory metals oxidize readily in air at high temperatures, so protective atmospheres, coatings, or alloys are typically used for high-temperature applications. Processing is challenging because of their very high melting points, which motivates techniques such as powder metallurgy and hot isostatic pressing.

Alloys and compounds based on refractory metals extend their practicality. Tungsten and its alloys are valued for filaments, heating elements, and crucibles, while molybdenum- and niobium-based systems are used in aerospace, chemical processing, and electrical components. Rhenium-containing alloys offer high-temperature strength in jet and rocket engine components. Niobium and tantalum are prominent in electronics, for example in capacitors, and tungsten carbide, a composite of tungsten with carbon, is a widely used hard material for cutting tools.

Overall, refractory metals enable performance in demanding high-temperature environments, albeit with processing and cost considerations.