Answer: Substitutional Impurity
Step-by-step explanation:
Substitutional impurity is a defect that occurs when a non-matrix atom replaces a matrix atom as did the zinc atoms in brass did to some copper atoms. These non-matrix atoms will then be called substitutional impurity atoms.
For this to happen, the non-matrix atoms have to be close in size to the matrix atom that they are replacing which in general means within a range of 15%.