Most metallic elements are best used in the alloyed form, for example, steel, brass, aluminum alloys. However some almost (99.5% or so) pure elements like semiconductors owe their properties to the presence of controlled amount of impurities in them. Metals seem to work as structural materials under loading conditions where sudden failures must be avoided. The metals are stronger than most plastics and have more toughness than most ceramics. Unlike Mechanical Engineers[?], Metallurgists study the microscopic mechanisms that cause a metal or alloy to behave in the way that it does, i.e. the changes that occur on the atomic level that affect the metal's (or alloy's) macroscopic properties.
Metallurgy is applied to electronic materials, as metals such as aluminum and copper are used in power lines, wires and the tiny electrical connections on computer chips. It is applied to welding and soldering, two techniques for joining metals.
Much effort has been placed on understanding one very important alloy system, Iron - Carbon, better known as steel.
Extractive metallurgy is the practice of separating metals, usually in the form of a metal-oxide, from their ore, and refining them into a pure metal. In order to convert a metal-oxide to a metal, the metal oxide must be reduced either chemically or electrolytically.