MOSSBAUER-SPECTROSCOPY APPLIED TO ICOSAHEDRAL QUASI-CRYSTALS

Thermodynamically stable Al-Cu-Fe and Fe-doped ferromagnetic Al-Cu-Ge- Mn icosahedral quasicrystals are studied by Fe-57 transmission Mossbau er spectroscopy and X-ray diffraction experiments. An Al65Cu20Fe15 qua sicrystalline alloy was subjected to a mechanical grinding (MG) for up to 800 h in a ball mill. The presence of an amorphous phase which co- exists with the quasicrystalline one is revealed in the early stage of MG. Mossbauer measurements were performed on icosahedral Al40Cu10-xGe 25Mn25Fex quasicrystal (x is-an-element-of [0.1; 3]) in a temperature range from 10 K to 548 K. It was found that a magnetic transition occu rs at about 30 K which is far below T, reported in the literature. It is concluded that AlGeMn ferromagnet which is present in the samples d oes not affect the magnetic transition observed and the transition is an intrinsic property of the Al-Cu-Ge-Mn host alloy.