1989 Volume 30 Issue 9 Pages 660-665
The latent heat of fusion ΔE and the entropy change on melting ΔS for metals with B.C.C. structure are systematically small compared with those for metals with F.C.C. structure. The entropy change on melting for the B.C.C. metals is about 0.76 of that for the F.C.C. metals. The mean distance between neighbouring atoms \barR observed experimentally in liquid F.C.C. metals is very close to the atomic distance Rs in the solid state at the melting temperature, but \barR in the liquid state of B.C.C. metals is considerably larger than Rs. The distribution of atoms in the liquid state of B.C.C. metals is shown experimentally to be in the same random close-packed arrangement as that in the liquid state of F.C.C. metals. From these facts, it may be supposed that B.C.C. metals transform to the liquid state through a transient stage of F.C.C. structure on melting. The latent heat of transition from the B.C.C. structure to the transient stage contributes to the reduction of the thermal energy necessary for fusion of the B.C.C. metals. From the above standpoint the latent heat of fusion and the entropy change on melting for the B.C.C. metals are evaluated in good agreement with the observed values for the alkali, alkali earth and other metals.
