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Precipitations of tungsten in quasicrystalline Al-Cu-Fe-W alloys

Jacek Krawczyk ,  Wojciech Gurdziel ,  Włodzimierz Bogdanowicz ,  Grzegorz Dercz ,  Robert Paszkowski 

University of Silesia, Institute of Materials Science (INOM), 75 Pułku Piechoty 1A, Chorzów 41-500, Poland

Abstract

The aim of presented paper is the analysis of precipitations morphology of tungsten in quasicrystal Al-Cu-Fe alloys. The composition of Al65Cu20Fe14W1 (at.%) was a base for preparation of bulk alloy in the form of ingot containing the icosahedral quasicrystalline phase.

The alloy was obtained in a two-stage process. At the first stage, the induction heating synthesis of alloy substrates and their preliminary homogenization were carried out using the mechanical mixing. The second stage was carried out by vertical directional solidification of the classic Bridgman method. The technological process was performed under protective atmosphere of helium (5N).

The samples were cut using electrical spark-erosion cutter. X-ray phase analysis, electron microscopy (SEM) and optical metallographic observations were performed.

The cubic β-phase, monoclinic λ-phase, quasicrystalline i-phase and tetragonal ω-phase were distinguished. It was stated that the needle-like precipitations of tungsten with the length-to-diameter ratio of 1:1000 were irregularly distributed in the volume of ingot. The presence of tungsten was confirmed by the powder phase analysis. The filaments of tungsten formed a clump-like aggregations. The tungsten filaments grow mainly on the crystalline β-phase.
 

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Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 2, by Wojciech Gurdziel
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-03-27 13:28
Revised:   2013-03-28 15:39