The General Kinetics of Cellular Decomposition of Lead—Tin Solid Solutions
S. P. Vorona, V. F. Mazanko, M. I. Savchuk, K. M. Khranovska, I. O. Shmatko, O. A. Shmatko
G.V. Kurdyumov Institute for Metal Physics, NAS of Ukraine, 36 Academician Vernadsky Blvd., UA-03142 Kyiv, Ukraine
Received: 29.04.2014; final version - 12.12.2014. Download: PDF
The general kinetics of the cellular precipitation from the Pb—Sn solid solutions containing 5.15, 7.60, 10.03, 12.38, 14.73, 19.22, 23.55, 27.70 or 29.05 at.% Sn is investigated at the temperature of 293 K by light microscopy, X-ray diffraction, and electrical resistance measurements. Ageing process in Pb—Sn alloys passes in two stages–primary and secondary cellular reactions. Primary cellular reaction results in a fine lamellar structure (cells) consisting of alternating tin lamellae and depleted lead-based solid solution. Then, the primary cellular structure is decomposed by means of the secondary cellular reaction or the interrupted coarsening. The secondary cellular reaction occurs at a much slower rate than the primary cellular reaction and results in a much coarser lamellar structure. Lattice-parameter measurements show the depleted lead-based solid solution in the primary cells having a composition far from equilibrium, while that in the product of secondary cellular reaction is close to equilibrium one. Representation of the initial experimental isothermal electrical resistivity plots for Pb—Sn ageing within the $d\rho/d\lg\tau-\lg\tau$ coordinates (where $\rho$ is electrical resistivity of alloy, $\tau$ is its ageing time) makes it possible to determine precise time intervals of primary and secondary cellular reactions and their rate parameters.
Key words: solid solution, aging, cellular decomposition, primary and secondary reaction.
PACS: 61.72.Cc, 61.72.Mm, 64.70.kd, 66.30.Fq, 66.30.Ny, 81.30.Mh, 81.40.Cd
Citation: S. P. Vorona, V. F. Mazanko, M. I. Savchuk, K. M. Khranovska, I. O. Shmatko, and O. A. Shmatko, The General Kinetics of Cellular Decomposition of Lead—Tin Solid Solutions, Metallofiz. Noveishie Tekhnol., 37, No. 1: 103—113 (2015) (in Ukrainian)