Examination of melting phases of copper and a new model of the liquid

Previously, diffraction transmission and scanning electron microscopy methods and probe microanalysis were used for the examination of melts of indium, gallium and tin. Examination by direct methods (in-situ) showed that the pre-melting stages characterised by spontaneous fragmentation of crystal grains into extremely fine elements. To some extent, this process is similar to the multiple nucleation of dislocation groups and maybe associated with the cascade-like increase of the number of bifurcations of the crystal potential in the pre-melting stage. Examination of the melts of indium and tin in liquid islands showed the presence of a crystalline phase with a size of #approx#2.5 nm. The second component of the liquid was found in the form of an amorphous film up to 3 nm thick. These results were used to formulate a new model of the liquid state. It is assumed that high superheating above the Debye temperature results in the formation of fluctuation waves of anomalous cooperative displacement of the atoms in crystals, as in the case of displacement detected in the stage of pre-transition processes. These anomalous displacements are possible as an alternative of thermal stresses of shear. In the Debye approximation for aluminium at room temperature they appear to be #approx#175 kg/mm"2. The self-organisation of the fluctuation displacement waves maybe regarded as the process of formation of a dissipative structure (DS), utilising the thermal energy of the crystal. It is assumed that the elements of the dissipative structure maybe represented by various defects of the crystal structure. Thus, the metallic melt is represented by a colloidal mixture inherited from the grains. As a result of the formation of a stable DS which consists of the several level of mosaic structure and 'divides' the crystal to mutually vibrating fragments, the crystals of the grains have the yielding property. The results of direct examination of the melting phases of indium, gallium and tin confirm the basic assumptions of this model. These metals have the well-known special features of the structure of the valency band, formed from electrons of s, p symmetry. In order to explain the special features of the application of these considerations to other elements, in this work, investigations were carried out into copper specimens whose valency band consists mostly of d-electrons (for the atom 3d"1"04s"1)Translated from Russian (Fiz. Khim. Obrab. Mater. 1996 (3) p. 30-33)Available from British Library Document Supply Centre-DSC:9023.190(VR-Trans--9061)T / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo