PHASE TRANSFORMATIONS IN MECHANICALLY ALLOYED Al-Cu-Cr POWDERS

摘要

Mechanical alloying was used to form a decagonal phase in the Al-Cu-Cr system. Elemental powders of Al_(67)Cu_(20)Cr_(13), Al_(75)Cu_(10)Cr_(15), Al_(65)Cu_(24)Cr_(11), Al_(69)Cu_(21)Cr_(10) and Al_(78)Cu_(10)Cr_(12) compositions (in at. %) 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 ψ-Al_(65)Cu_(25)Cr_(10) phase, which is an approximant phase to icosahedral quasicrystal.