Papers by Keyword: Phase Growth

Abstract: The suppression criterion of the binary phase growth due to addition of a third component is considered. In this case the analysis of the two possible criteria of the first phase growth are considered: first – kinetic criterion based on the balance of components fluxes and second - thermodynamic criterion which is based on the maximal rate of the entropy production principle. We demonstrate that in the case of a model system the thermodynamic criterion lead to a bigger value of the critical thickness of the phases which are suppressed by the growth of the investigated phase.

Abstract: Traditional theories of interdiffusion in solids based on Fick’s first and second laws and Darken’s equations can not describe the relationship between the diffusion fluxes and the diffusion-induced stresses, because the subject matter of the traditional theories is the diffusing atom or atomic flux, not the volume unit within the interdiffusion field. For this reason, it is suggested that the concept of flow point in the interdiffusion field should be constructed to describe the diffusion-induced stresses and the phase growth.

Abstract: The reaction between the zinc plate (ZP) and the IF steel with near surface ultra fine grains (NSUFG) structure with grain size of about 89 nm was studied in temperature range of 473K to 623K in order to elucidate the temperature dependence of the reactions and its mechanism, by comparison with the reactions of ZP to coarse grains (CG) sheet, superficial cold rolled CG sheet (CG+R) and superficial cold rolled NSUFG sheet (NSUFG+R). It was found that this NSUFG structure considerably affected reactions between IF steel and ZP. There was almost no effect of superficial cold rolling on their reactions, but the NSUFG structure dramatically enhanced the reactions. The incubation times for appearance of the reaction layer and its layer width of ZP /(NSUFG or NSUFG+R) reactions are shorter and thicker than those of the ZP/(CG or CG+R) ones. The activation energy for reaction was 107kJ/mol, which indicates that the volume diffusion in zinc side and the grain boundary diffusion in the iron side play an important role in the reaction. The layer growth up to the layer thickness less than about 10µm was controlled mainly by the interface reaction and it over about 10µm mainly by the diffusion mass transfer.