What is the structural difference between alloys and pure metals?

Alloys are mixtures of two or more metals, while pure metals consist of only one type of metal atoms.

In a pure metal, the atoms are arranged in a regular, repeating pattern which forms a metallic lattice. This structure allows the metal atoms to slide over each other easily, making pure metals malleable and ductile. However, this also makes pure metals relatively soft and weak. For example, pure gold and silver are too soft to be used for jewellery or coins, so they are often alloyed with other metals to increase their strength.

Alloys, on the other hand, are made by melting two or more metals together, allowing the atoms of the different metals to mix. The resulting structure is irregular, as the atoms of the different metals are different sizes. This disrupts the metallic lattice, preventing the atoms from sliding over each other as easily. This makes alloys harder and stronger than pure metals. For example, steel is an alloy of iron and carbon that is much stronger than pure iron.

Furthermore, alloys often have properties that are different from those of their component metals. For example, bronze is an alloy of copper and tin that is harder than either copper or tin alone. Similarly, brass is an alloy of copper and zinc that is more corrosion-resistant than either copper or zinc alone. This ability to tailor the properties of alloys by changing their composition is one of the reasons why alloys are so widely used in industry.

In summary, the main structural difference between alloys and pure metals is that pure metals have a regular, repeating structure, while alloys have an irregular structure due to the presence of different types of atoms. This difference in structure is what gives alloys their superior strength and other desirable properties.