What is an alloy? Why do we need an alloy?

Hint: Iron in its pure form is weak and cannot be used in industries. Whereas steel is widely used in industries. It is hard and has high tensile strength. Steel is an alloy of iron. It contains other elements like manganese in it.

Complete step by step solution:
> The homogenous mixture of two or more metals is called an alloy. It has different physical and chemical properties than the constituent metals. The alloy once formed can’t be separated into its constituent elements by physical means.
Some examples of alloys are steel, brass, bronze, etc.
> Steel is an alloy of Fe, Cr or Ni and Mn.
> Alloys are extensively used in metal industries, construction industries, etc.
> Let’s look at the need and importance of alloys:
- The metals in their pure form are highly reactive and corrosive in nature. Iron in its pure form is not as hard as steel which is its alloy.
- Alloys of the metals have improved properties than the major constituent metals. They are also resistant to corrosion.
- Alloys have high tensile strength unlike metals and can be extensively used in industrial work.
Hence, we need alloys as replacement for pure metals because metals cannot be used directly in pure state.

Note: Transition metals are usually used to make alloys because of their almost similar sizes. They get easily fixed into the interstitial spaces and replace the other metal atom.
Examples of alloying metals are Cr, Mo, V, Mn and Ni.