Metalle

Metalle, or metals, are a class of elements characterized by high electrical and thermal conductivity, luster, malleability, and ductility. In the solid state they typically form crystalline structures with a sea of delocalized electrons that enables metallic bonding. Most metals are found in the Earth's crust as minerals and must be extracted and refined to obtain usable metal.

Metals are commonly divided into ferrous and non-ferrous categories. Ferrous metals primarily contain iron and are known for strength and magnetic properties; examples include steel and cast iron. Non-ferrous metals, which do not contain iron as a major component, include aluminium, copper, zinc, tin, lead, nickel, and titanium. Within these groups, additional labels exist: light metals (low density such as aluminium and magnesium), heavy metals, and precious metals (gold, silver, platinum).

Extraction and processing: Metals occur as ores in the crust. They are extracted through mining, then refined by processes such as smelting, electrolysis, or chemical reduction to remove impurities. Secondary production from recycling also plays a major role, especially for aluminium and steel, reducing energy use and environmental impact.

Alloys: Many metals are combined with other elements to form alloys that enhance properties such as strength, hardness, or corrosion resistance. Examples include steel (iron with carbon and other elements), bronze (copper and tin), brass (copper and zinc), and various aluminium alloys. Forming processes include casting, forging, rolling, and extrusion; heat treatment can modify microstructure and performance.

Applications and considerations: Metals are essential in construction, transportation, electronics, and machinery. Their properties also pose challenges, including susceptibility to corrosion, fatigue, and environmental concerns related to mining and refining. Sustainable metal use emphasizes efficient extraction, recycling, and responsible stewardship of resources.