Description of Kinetics of Cellular Decomposition of Supersaturated Solid Solutions for Pb—Sn Alloy
M. O. Ivanov, A. Yu. Naumuk, O. A. Shmatko
G.V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03680 Kyiv-142, Ukraine
Received: 20.06.2014. Download: PDF
Based on the approach, which was previously developed by the authors to describe the kinetics of cellular decomposition of solid solutions, in this paper, a comparison of theoretical and experimental data on the temperature dependences of various characteristics of such a process is carried. Experimental data on the ageing of Pb—27.07 at.% Sn alloy is selected as an object of comparison. To determine the driving force of the process, a simple model of pair interatomic interactions of the nearest neighbours is used. As shown, the temperature dependences of front velocity and the heat-release rate are described, in accordance with the experimental data, by curves with maxima, whose positions are determined by competition between the driving force and the decomposition front boundary diffusion coefficient for tin. The activation energy for such diffusion is found to be of order of 0.27 eV and is in agreement with values obtained by other methods. The shift of the maximum of thermal effect with respect to the maximum of front velocity towards lower temperatures, which is observed experimentally, is described theoretically. As also shown, the values of interlamellar spacings measured in the experiment correspond to the secondary cellular decomposition processes.
Key words: cellular decomposition thermal effect, boundary diffusion, rate of change of free energy, cellular decomposition front velocity, lamellar structure, supersaturated solid solutions.
PACS: 64.60.A-, 64.60.My, 64.75.Nx, 65.40.gd, 65.40.gp, 66.30.Fq
Citation: M. O. Ivanov, A. Yu. Naumuk, and O. A. Shmatko, Description of Kinetics of Cellular Decomposition of Supersaturated Solid Solutions for Pb—Sn Alloy, Metallofiz. Noveishie Tekhnol., 36, No. 8: 1059—1077 (2014) (in Russian)