How is an alloy defined?

An alloy is defined as a mixture of two or more metals or a metal and another element. This definition captures the essence of alloys, which are typically created to enhance certain properties such as strength, ductility, corrosion resistance, or conductivity, which are often superior compared to those of the individual metals alone. For example, steel is an alloy made primarily of iron and carbon, while bronze is composed of copper and tin.

By identifying alloy composition in this way, it allows for a wide range of properties and applications depending on the specific metals or elements combined. Alloys are crucial in various industries, from construction to electronics, where tailored material properties are vital for performance and durability.

The other options do not accurately reflect the definition of alloys. A pure metal does not qualify as an alloy, nor does a substance that cannot be broken down into simpler substances. These definitions either restrict the concept too much or mischaracterize the nature of alloys altogether.