Among the strongest intermolecular forces are ionicbonds. ... These oppositely charged compounds are held together by strong electrostatic forces of attraction. As these forces are very strong, a considerable amount of heat energy is required to break them. Hence, ionic compound have a high melting point.
Metals such as gold(Au) platinum(Pt) present at the bottom of the activity series do not corrode easily.
Alloys are homogeneous mixtuers of two or more elements. The elements could be two metals or a metal and a non metal. An alloy is formed by first melting the metal then dissolving the other elememts in it. For example steel is an alloy of iron and carbon.