What is an alloy?

An alloy is defined as a mixture of two or more metals, and this definition highlights the essential nature of alloys in materials science. Alloys are created to enhance certain properties that pure metals may not possess, such as increased strength, improved corrosion resistance, or lower weight. For instance, steel is an alloy made primarily of iron and carbon, which significantly increases its strength compared to pure iron.

In contrast, the other options do not accurately capture what an alloy is. A type of pure metal refers to individual substances with uniform composition, which does not involve a combination of different metals. A form of gas is completely unrelated to the concept of alloys, as alloys are solid materials. Finally, a solid metal structure might imply a specific form or arrangement of metal rather than the mixing of multiple metals, which is central to the concept of an alloy. Thus, understanding alloys as mixtures of metals is fundamental when studying materials and their applications in various fields.