Phason strains on growth, stability and structure of icosahedral phases

Growth, stability and structure of icosahedral (i-) phases have been studied by electron diffraction and X-ray diffraction in relation with the phason strains. Three alloy systems; AlPdCr, AlPdMn and AlCuV were chosen in this study. An i- Al₇₂Pd₂₅Cr₃ grain has been analysed to have a phason matrix toward to a tetragonal or orthorhombic structure. Stability of the i-phases correlated with the phason relaxation was discussed in Al-Pd-Mn system. A quenched i-Al₇₄Pd₁₇Mn₉ close to but containing significant phason strains, revealed that the phason relaxation induced by precipitation of crystalline phases upon annealing. Phason disorder dominated by the chemical composition was evidenced in a composition study in Al-Pd-Mn system. A high density random phasons characterized the icosahedral glass phase was observed in AlCuV alloys.