Based upon new results of the position of the upper limit of the α–α′ miscibility gap, the positions of the (i) metastable αm–α′m miscibility gap and (ii) chemical as well as coherent spinodal curves are recalculated. Furthermore, the position of the so‐called ‘spinodal of GP zones’ is determined by means of latest experimental data. It turned out that by use of the applied methods (i) all the calculated curves are in a “reasonable” order and (ii) the positions of the coherent spinodal curve and the “spinodal of GP zones” are not far from each other.

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The diffusion-controlled n-dimensional growth (n = 1; 2; 3) in a finite matrix is considered solving the diffusion equation (DE) in the approximation of the stationary solution and having regard to the mass balance of the alloyed atoms. The results are compared with those obtained for the infinite matrix as well as for the non-stationary solutions of the DE. The derived results show that the method applied in this work is a useful approach to gaining information on the diffusion-controlled growth of precipitates.Das diffusionskontrollierte n-dimensionale Wachstum (n = 1 ;, 2; 3) von Ausscheidungen in einer begrenzten Matrix wird untersucht in der Naherung der stationaren Losung der Diffusionsgleichung (DE) und des Massengleichgewichts der zulegierten Atome. Die Resultate werden mit denjenigen verglichen, die sowohl fur eine unendliche Matrix als auch aus den nichtstationaren Losungen der DE abgeleitet werden. Die gewonnenen Ergebnisse zeigen, daI3 die in dieser Arbeit verwendete Methode ein zweckmlI3iger Schritt fur die Gewinnung von Aussagen uber das diffusionskontrollierte Wachstum von Ausscheidungen ist.