Chapter 7, Problem 92A

Interpretation Introduction

Interpretation:

The reason for zinc and copper to be used as substitutional and not interstitial alloy needs to be explained.

Concept introduction:

When there is combination of metals or metals that are combined with one or more elements then we get alloy. The elements like gold, silver, iron, non metallic carbon, combined with other elements to give alloys. Alloys have properties which have increased strength and hardness, corrosion resistance, and have good mechanical strength. It is used in buildings, tools, automobiles, etc.

Answer to Problem 92A

Copper and zinc have the same size and therefore will substitute certain empty spaces and cannot form interstitial alloys as it cannot get into the spaces between the lattice points

Explanation of Solution

There is two mechanism when molten metal is mixed with another substance, namely exchange of atoms or interstitial mechanism. Depending on the size of the atom, the mechanism will be utilized.

The exchange of atom happens when the atoms are of similar size and substitution of atoms in metallic crystals, it is substitutional alloy.

The size of copper and zinc ions are similar. Hence, it can replace each other forming substitutional alloy.

Example is Brass and Bronze.

But the copper and zinc will not form interstitial alloy as the size of the atoms are such that it will not fit it self in between the interstitial space.

Conclusion

Copper and zinc have the same size and therefore will substitute certain empty spaces and cannot form interstitial alloys as it cannot get into the spaces between the lattice points