if one of the elements is small enough to fit between the larger atoms then it forms an interstitial .
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.
Alloys that contain only copper and zinc are usually called "brass"; there are also some alloys that contain one or more other metals in addition to copper and zinc, and these usually have another...