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Abstract. Mechanical alloying was applied to form a decagonal phase in the Al--Cu--Cr system. were mechanically alloyed in a planetary ball mill. Annealing in the temperature range of 500 to 550 C results in the formation of binary and ternary compounds including the decagonal quasicrystalline phase that was found to be stable at least up to 800 C and was present in various amounts in all investigated alloys. No icosahedral quasicrystalline phase was found in the samples. The maximum content (95 vol%) of decagonal quasicrystalline phase was observed for Al 69 Cu 21 Cr 10 compound annealed at 635 C. Further increase in the annealing temperature results in the quasicrystalline phase transformation into w-Al 65 Cu 25 Cr 10 phase, which is an approximant phase to icosahedral quasicrystal.

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X-ray diraction analysis, scanning and transmission electron microscopy, thermal analysis and measurement of chemical composition were implemented to determine structure, thermal stability and chemical composition of the decagonal quasicrystal in Al73Cu11Cr16 alloy produced by long-term mechanical alloying of elemental powders followed by annealing at 700• C. According to the TEM investigation such a technique permits to produce a single-phase nanostructural quasicrystal with grain size about 60 nm. Dierential thermal analysis revealed that the decagonal phase does not exist above 923• C and undergoes incongruent two-stage melting coming to the end at 1100• C.