Homogeneous melting of metals with different crystalline structure

Numerical simulations have been used to investigate the thermal response to a gradual temperature rise in surface-free bulks of metallic elements with different crystalline structure. The increase in thermal vibration amplitudes determines the appearance of atoms with defective coordination. Their number increases with temperature at a rate depending on the thermal properties of the crystalline lattice. Due to the absence of free surfaces and other structural defects, melting takes place at the first limit of superheating. Numerical findings point out that, at such a temperature, elements with the same crystallographic structure display roughly the same content of atoms with defective coordination. The fraction of defectively coordinated atoms at the homogeneous melting point is then a quantity characteristic of the crystalline lattice. The relationship between the homogeneous and the heterogeneous melting points is also discussed in the light of the different mechanisms underlying the melting processes.