Dodecahedral-shaped quasicrystalline precipitates in dilute Al-Mn solid solutions

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Abstract
The Al-Mn icosahedral phase is found to precipitate and grow at room temperature from rapidly quenched Al-4 at % Mn f.c.c. solid solutions, with the composition 13•5 ± 1•5at.%Mn, the surrounding matrix having a composition of 3•1 ± 0•3 at.% Mn. Dodecahedral-shaped precipitates with orientation relationships with the f.c.c. matrix are produced. The above information is rationalized in terms of symmetry arguments and growth processes. Comparison of the compositions obtained here with that of other work extends our knowledge of the Al-Mn metastable equilibrium between the icosahedral phase and the f.c.c. Al-Mn solid solution in the solid state.