What is the primary reason for alloying metals?

The primary reason for alloying metals is to increase their resistance to corrosion. Alloys often contain a combination of different elements that enhance various properties of the base metal, including its strength, hardness, and especially its ability to withstand environmental degradation. Many metals, when exposed to moisture and oxygen, can oxidize or corrode; however, by creating an alloy, you can introduce elements that form a protective layer or change the electrochemical properties of the metal, which reduces the rate of corrosion.

For instance, stainless steel is an alloy made primarily of iron with a certain percentage of chromium. The chromium reacts with oxygen to form a thin, stable layer of chromium oxide on the surface, preventing further corrosion of the underlying steel.

In contrast, while changing color, lowering melting points, and enhancing magnetism can be secondary benefits of certain alloys, these are not the primary motivating factors in metallurgy when it comes to the overall performance and durability of materials used in practical applications.