Ion induced formation of the quasi-crystalline structure in Al-transition metal systems

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5337928

Lilienfeld, D A

At the onset of this investigation, it was well established that quasicrystalline AlMn, exhibiting the 5-fold diffraction patterns of icosahedral symmetry, could be formed from the liquid phase by rapid quench. The objective of this study was to determine if quasicrystalline AIMn could be formed from the solid phase using thin-film and ion-radiation techniques. Using these procedures, it was found that the quasicrystalline structure could be formed by a solid phase transformation of Al/sub 84/Mn/sub 16/ by either thermal annealing or ion irradiation at elevated substrate temperatures. Ion irradiation produced the more complete transformation and became the focus of the next aspect of the study on the parameters that govern the formation of quasicrystals. The author used Al/sub 84/Mn/sub 16/ as the starting point and investigated adjacent transition metals Cr and Fe and compositions from Al/sub 90/Mn/sub 10/ to Al/sub 70/M/sub 30/. Icosahedral patterns with five-fold rotational symmetry were found in ion-irradiation (150/sup 0/C) Al/sub 85/Cr/sub 15/ layers. The alloy Al/sub 83/Fe/sub 1/ was also shown to form quasicrystals by Xe ion irradiation (175/sup 0/C) of amorphous layers. The three alloy systems - AlCr, AlMn and AlFe - that form quasicrystals were examined by electron diffraction following the indexing scheme used in the x-ray diffraction analysis of liquid-phase quenched AlMn. The reciprocal lattice spacings are found to be nearly the same, indicating that the systems are isostructural.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 5337928
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360106* -- Metals & Alloys-- Radiation Effects
ALLOYS
ALUMINIUM ALLOYS
ANNEALING
CHARGED PARTICLES
CHROMIUM ALLOYS
CRYSTAL STRUCTURE
HEAT TREATMENTS
HIGH TEMPERATURE
IONS
IRON ALLOYS
MANGANESE ALLOYS
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS