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Abstract
The quasicrystals represent a new type of solids, characterized by the presence of an orientational symmetry of order five accompanied by the absence of translational periodicity. The quasicrystals present many surprising and interesting physical properties.
The aim of this thesis is to produce the quasicrystalline phase in the AlCuFe alloy with the composition Al62.5 Cu25 Fe12.5 by the mechanical alloying (MA). Three methods of production were used, the rapid solidification, the rapid solidification followed by milling and the mechanical alloying. The obtained phases were characterized by the X-rays diffraction (XRD). The thermal stability of some samples was examined by the differential thermal analysis (DTA). The electrical resistivity and its variation with temperature were measured for the samples prepared by rapid solidification (in form of ribbons).
The sample prepared by rapid solidification, after annealing, contains two phases ( quasicrystalline phase [ i-phase ] + ω phase ), the formed i-phase was stable phase.
The milling of the sample prepared by rapid solidification (after annealing at 8000 C) reduces the volume fraction of the ω phase and increases that of the i-phase. But, further milling results in the formation of some other phases beside the i-phase.
For the sample prepared by mechanical alloying, it was not possible to obtain the i-phase as a single phase. But it can be obtained as a dominant phase after certain conditions of milling and annealing. Further milling or further annealing results in the transformation of this i-phase into the more stable ω phase.