Abstract
Microstructural changes resulting from isothermal decomposition of the β-phase have been studied in Cu-rich binary Cu-Al and ternary Cu-Al-Sn alloys containing up to 3 at.% Sn at temperatures from 873 to 673 K. Results are presented as TTT diagrams. The decomposition occurs in several stages, each of which involves the establishment of metastable equilibrium between β and one or more of the product phases α β1 and γ2. Addition of Sn has been shown to increase the stability of the ordered β1-phase in relation to β. In alloys containing more than 2 at.% Sn, the β1 emerges as a stable phase. At low Sn concentrations β1 is metastable. An important new finding is the existence of three-phase equilibrium microstructure containing α β1 and γ2. Increasing addition of Sn alters the morphology of β1 from rosettes to dendrites and finally to Widmanstätten needles.
References
[1] C.S.Smith, W.E.Lindief: Trans. AIME104 (1933) 69.Search in Google Scholar
[2] E.S.Davenport, E.C.Bain: Trans. AIME, 90 (1930) 117.Search in Google Scholar
[3] D.L.Thomas: J. Inst. Metals, London94 (1966) 250.Search in Google Scholar
[4] G.Wassermann: Metallwirtschaft13 (1934) 133.Search in Google Scholar
[5] D.R.F.West, D.L.Thomas: J. Inst. Metals, London83 (1955) 505.Search in Google Scholar
[6] J.R.Moon, R.D.Garwood: J. Inst. Metals, London96 (1968) 17.Search in Google Scholar
[7] J.S.L.Leach, G.V.Raynor: Proc. Roy. Soc. London224 (1954) 251. 10.1098/rspa.1954.0155Search in Google Scholar
[8] N.R.Bochvar: in G.Petzow, G.Effenberg (Eds.): Ternary Alloys-A Comprehensive Compendium of Evaluated Constitutional Data and Phase Diagrams, 1992, vol. 5, p. 23, VCH Verlagsgesellschaft, Weinheim, FRG.Search in Google Scholar
[9] C.Laird, H.I.Aaronson: Acta Metall.4 (1969) 505. 10.1016/0001-6160(69)90032-7Search in Google Scholar
[10] G.Horvay, J.W.Cahn: Acta Metall.9 (1961) 695. 10.1016/0001-6160(61)90008-6Search in Google Scholar
© 2013, Carl Hanser Verlag, München
