On the properties of the amorphous state of a single-component substance

Abstract

It is shown that on the nonlinear dependence of the first coordination number (kn) versus the packing coefficient (kp) of the structure of a single-component substance, three special points corresponding to the amorphous structures can be distinguished. Based on the pairwise interatomic potential of Mie–Lennard-Jones, the state equation and properties of iron for both these three amorphous structures and the crystal state are calculated. It is shown that at kp = 0.45556 and kn = 6.2793 the minimum chemical potential is reached, i.e. this point is corresponding a thermodynamically stable amorphous structure into the liquid phase. An energetically equivalent point with the same kn value, but with kp = 0.6237, is a thermodynamically unstable amorphous structure corresponding to the solid phase. The following properties are calculated for amorphous iron: specific volume, chemical potential, entropy, Debye temperature, elastic modulus, thermal expansion coefficient, isobaric heat capacity, surface energy, and Poisson's ratio. It is shown that the specific surface energy of an amorphous solid metal is greater than that of an amorphous liquid phase, but less than that of a metal in the crystalline state. This should lead to the fact that the surface of the crystal metal should tend to amorphization.