Alloys

An alloy is a substance composed of two or more elements, where at least one is a metal. Alloys are designed to achieve properties that are different from or superior to those of the constituent elements alone. Most alloys are solid mixtures or compounds formed by combining elements and allowing them to solidify, or by mechanical processing of powders. Common examples include steel (iron and carbon, often with other elements such as chromium, vanadium, or nickel to improve strength and durability), bronze (copper and tin), and brass (copper and zinc). Aluminum alloys add elements such as magnesium or silicon to increase strength while reducing weight; titanium alloys combine titanium with elements like aluminum and vanadium to improve high-temperature performance.

Alloys are typically engineered through melting and alloying, followed by careful cooling. Heat treatments such as annealing, solution treating, and precipitation hardening can further tailor their properties. They are distinguished from pure elements and from chemical compounds by being mixtures of elements with properties not present in any single element.

Applications are broad and include construction materials, automotive and aerospace components, machinery, and consumer electronics. Advantages of alloys include higher strength, improved hardness, better wear and corrosion resistance, and adjustable ductility. Limitations can include higher cost, more complex processing, potential brittleness, and recycling challenges.

Historically, alloys such as bronze and steel have played central roles in technological development. Modern alloy development continues to target specific performance criteria for demanding environments.