alloy

An alloy is a substance composed of two or more elements, where at least one is a metal, designed to obtain properties that are better suited to specific uses than those of the constituent elements. Alloys are typically formed by melting the components, combining them in precise proportions, and allowing the mixture to solidify; some are made by mechanical blending or by diffusion at lower temperatures. Most alloys are homogeneous, forming a single solid solution or phase, but some consist of multiple phases with distinct microstructures.

The main purpose of alloying is to improve properties such as strength, hardness, wear resistance, or corrosion resistance, or to alter melting points and density. Carbon is the principal alloying element in steel, where varying carbon content and other elements control hardness and ductility. Stainless steels add chromium and often nickel for corrosion resistance. Copper-based alloys include bronze (copper and tin) and brass (copper and zinc). Aluminum and titanium alloys use elements such as magnesium, silicon, or vanadium to reduce weight and increase strength. Nickel-based and cobalt-based alloys are important in high-temperature or demanding environments.

Alloys have wide applications in construction, transportation, aerospace, machinery, tools, and consumer electronics. They also enable cookware with specific heat and wear properties. The concept dates to ancient metalworking, with the Bronze Age marking a major early use of alloying.