Formation of decagonal quasicrystals in mechanically alloyed Al-Cu-Cr powders

摘要

Mechanical alloying was applied to form a decagonal phase in the Al-Cu-Cr system. Elemental powders of Al67Cu20Cr13, Al75Cu10Cr15, Al65Cu24Cr11, Al69Cu21Cr10 and Al78Cu10Cr12 compositions (in at%) were mechanically alloyed in a planetary ball mill. Annealing in the temperature range of 500 to 550 degrees 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 degrees 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 quasicrystal line phase was observed for Al69Cu21Cr10 compound annealed at 635 degrees C. Further increase in the annealing temperature results in the quasicrystalline phase transformation into psi-Al65Cu25Cr10 phase, which is an approximant phase to icosahedral quasicrystal.