Metal A (atomic radius 135 pm) is alloyed with a small amount of metal B (100 pm)
CHEMISTRY · Single correct · GCSE · Chemistry · Bonding, Structure and the Properties of Matter · Bonding, Structure and the Properties of Matter
Problem
Metal A (atomic radius 135 pm) is alloyed with a small amount of metal B (100 pm). Using the commonly cited 15 % atomic-size guideline, B atoms in the solid solution are most likely to
(a) Replace A atoms, forming a substitutional alloy, because the size difference is only about 7%.
(b) Segregate into a separate intermetallic phase, because the 26 % size difference exceeds the 15 % guideline and B is still too large to fit the lattice holes.
(c) Occupy interstitial sites, forming an interstitial alloy, because the size difference is about 26%.
(d) Form an ionic lattice with A atoms, since metallic bonding would be disrupted by the 26 % size mismatch.