Influence of boron content on the microstructure of sintered Al 62.5-x Cu 25.3 Fe 12.2 B x alloys ( x = 0, 3, 5)
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erbst Laboratoire de Sciences et Génie des Surfaces, UMR 7570, CNRS-INPL-EDF, Parc de Saurupt, ENSMN, 54042 Nancy Cedex, France
P. Weisbecker, J-B. Ledeuil, M.C. de Weerd, F. Machizaud, and J-M. Dubois Laboratoire de Science et Génie des Matériaux et de Métallurgie, UMR 7584, CNRS-INPL-UHP, Parc de Saurupt, ENSMN, 54042 Nancy Cedex, France (Received 7 May 2004; accepted 16 June 2004)
Microstructures and morphological features of a series of sintered quasicrystalline Al62.5−xCu25.3Fe12.2Bx alloys, with x ranging from 0 to 5 at.% were studied using x-ray diffraction, scanning electron microscopy, x-ray mapping, and electron probe microanalysis. Electron backscattering diffraction (EBSD) was also used to get information about the structures of some phases and identify the crystalline relationship in-between phases. Increasing x results in the change of the nature of extra phases. These secondary phases are all less than 1% in volume of the total matter except for the  phase at 5% of boron. Whatever the percentage of boron considered, boron seems to concentrate essentially in the parasite phases confirming doubts found in literature about the solubility of boron inside the face-centered-icosahedral Al–Cu–Fe phase. No special crystallographic relationship in between the tested phases could be spotted. EBSD is thus also confirmed as an excellent technique to get quasicrystalline grains orientations.
I. INTRODUCTION
Quasicrystalline phases were discovered in 1984.1 The particular feature of this new class of materials is its unique tendency to crystallize according to nonperiodic crystallographic structures (icosahedral, decagonal …).1–3 These structures exhibit a long-range order that is not compatible with translation and impart a brand new combination of properties4–14 to the material. This new combination of properties is as new as it is varied, considering they are made of metallic atoms. Transport (thermal, electronic, optic …), tribological and thermodynamic properties have been widely investigated and found to be very original. Since this is a rather critical point for possible industrial applications, their mechanical properties are also of high interest. Although these quasicrystalline intermetallic compounds can be plastically deformed at high temperature, they are very brittle at room temperature. Their hardness is high and the toughness is rather low (Refs. 15–17 give data for the Al–Cu–Fe phase). a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0366 2974
J. Mater. Res., Vol. 19, No. 10, Oct 2004
However, some work18 mentioned that the addition of boron to Al–Cu–Fe icosahedral quasicrystal helps to modify their fragility: while it simultaneously increases hardness values, addition of boron notably improves the fracture toughness of quasicrystalline coatings formed by plasma arc spraying. Different microstructural studies were performed in an attempt to understand such behavior. Sordelet et al.19 have studied the related microstructures of sample
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