Disorder in Al-Mn-Fe icosahedral alloys introduced by iron

Journal Article · Tue Jun 01 00:00:00 EDT 1993 · Microscopy Research and Technique; (United States)

DOI:https://doi.org/10.1002/jemt.1070250215· OSTI ID:6137569

Nistor, L C; Teodorescu, V; Manaila, R ^[1]

---

1. Inst. of Atomic Physics, Bucharest (Romania)

Considerable effort is directed nowadays towards obtaining large and perfect icosahedral phases (IP), in order to study their specific properties related to the lack of translational periodicity. However, real IP in the most Al-TM systems (TM = transition metal) contain structural defects, which clearly differentiate them from the ideal ones. In local models for describing quasicrystals the IP is assumed to be a 3D network of complex Mackay icosahedra connected through faces and vertices. Here the quasiperiodical order becomes apparent by the parallelism of the interatomic bonds in the neighboring icosahedra. Local models introduce also an element of randomness by assuming a statistic occupancy of the icosahedral faces and vertices. Thus different but equivalent ways to built an assembly of icosahedra appeared to be the cause of an intrinsic topological disorder and the spatial correlation of icosahedra in a real IP would be limited to regions of pseudocoherence. In the limit of the highest disorder a real quasicrystal approaches a dense random packing of icosahedra or fragments of them. The specific icosahedral order would be disrupted by localized defects (local violation of the matching rules), broadly classified as phonon and phason strains. In the IP phason strains are definitely more significant as they measure the degradation of the icosahedral order with respect the ideal one, i.e. the ability to stabilize an icosahedral phase for a certain composition. It is the purpose of this paper to demonstrate some of these concepts.

• OSTI ID: 6137569
• Journal Information: Microscopy Research and Technique; (United States), Vol. 25:2; ISSN 1059-910X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
ORDER-DISORDER TRANSFORMATIONS
IRON ALLOYS
MANGANESE ALLOYS
CRYSTAL DEFECTS
ELECTRON DIFFRACTION
MICROSTRUCTURE
PHONONS
RANDOMNESS
TERNARY ALLOY SYSTEMS
TRANSMISSION ELECTRON MICROSCOPY
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON MICROSCOPY
MICROSCOPY
PHASE TRANSFORMATIONS
QUASI PARTICLES
SCATTERING
360102* - Metals & Alloys- Structure & Phase Studies