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Long-period structures in gold-copper alloys; Structures a longues periodes dans les alliages or-cuivre

Abstract

We first proceed to reevaluation of the gold-copper equilibrium diagram for alloys between Au{sub 20}Cu{sub 80} and Au{sub 65}Cu{sub 35}. The identification of the various phases was performed by X-rays diffraction on quenched polycrystalline samples. We next study the structure of the phase AuCuII. X-ray data collected from bulk single crystals show that this long-period structure must be described with the help of two correlated periodic functions: an 'order function' and a 'displacement function'. The 'order function' conciliates the non-integer value of the period with its rigorous definition. The 'displacement function' accounts for the dis-symmetries of the observed intensities for the antiphase homologous reflections as the appearance of satellites around the fundamental reflections. These two functions are remarkably well defined at long distance in carefully annealed samples and, in some conditions, can be obtained independently. We observe that the improvement of the degree of order increases the 'modulation of position'. In the case of non stoichiometric alloys, the excess of gold atoms (gold rich alloys) is distributed at random whereas the excess of copper (copper rich alloys) is distributed in a preferential manner close to the antiphase boundaries. (author) [French] Nous procedons, tout d'abord, a une reevaluation du diagramme d'equilibre  More>>
Authors:
Jehanno, G [1] 
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
Publication Date:
Jul 01, 1965
Product Type:
Thesis/Dissertation
Report Number:
CEA-R-2812
Resource Relation:
Other Information: 45 refs
Subject:
36 MATERIALS SCIENCE; BINARY ALLOY SYSTEMS; COPPER BASE ALLOYS; CRYSTAL STRUCTURE; GOLD BASE ALLOYS; ORDER-DISORDER TRANSFORMATIONS; PHASE DIAGRAMS
OSTI ID:
20650653
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France); Faculte des Sciences de l'Universite de Paris, 75 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR05R2812090266
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
[83] pages
Announcement Date:
Nov 23, 2005

Citation Formats

Jehanno, G. Long-period structures in gold-copper alloys; Structures a longues periodes dans les alliages or-cuivre. France: N. p., 1965. Web.
Jehanno, G. Long-period structures in gold-copper alloys; Structures a longues periodes dans les alliages or-cuivre. France.
Jehanno, G. 1965. "Long-period structures in gold-copper alloys; Structures a longues periodes dans les alliages or-cuivre." France.
@misc{etde_20650653,
title = {Long-period structures in gold-copper alloys; Structures a longues periodes dans les alliages or-cuivre}
author = {Jehanno, G}
abstractNote = {We first proceed to reevaluation of the gold-copper equilibrium diagram for alloys between Au{sub 20}Cu{sub 80} and Au{sub 65}Cu{sub 35}. The identification of the various phases was performed by X-rays diffraction on quenched polycrystalline samples. We next study the structure of the phase AuCuII. X-ray data collected from bulk single crystals show that this long-period structure must be described with the help of two correlated periodic functions: an 'order function' and a 'displacement function'. The 'order function' conciliates the non-integer value of the period with its rigorous definition. The 'displacement function' accounts for the dis-symmetries of the observed intensities for the antiphase homologous reflections as the appearance of satellites around the fundamental reflections. These two functions are remarkably well defined at long distance in carefully annealed samples and, in some conditions, can be obtained independently. We observe that the improvement of the degree of order increases the 'modulation of position'. In the case of non stoichiometric alloys, the excess of gold atoms (gold rich alloys) is distributed at random whereas the excess of copper (copper rich alloys) is distributed in a preferential manner close to the antiphase boundaries. (author) [French] Nous procedons, tout d'abord, a une reevaluation du diagramme d'equilibre des alliages or-cuivre compris entre Au{sub 20}Cu{sub 80} et Au{sub 65}Cu{sub 35}. L'identification des differentes phases s'est faite par diffraction de rayons X sur des echantillons polycristallins trempes. Nous etudions ensuite, aux rayons X, la structure de la phase AuCuII. Les donnees rassemblees sur monocristaux massifs indiquent que cette structure a longue periode doit etre decrite a l'aide de deux fonctions periodiques correlees: une fonction d'ordre et une fonction de deplacement des atomes. La fonction d'ordre concilie le caractere non entier de la periode avec sa rigoureuse definition. La fonction de deplacement justifie les dissymetries d'intensites observees pour les reflexions d'antiphase homologues et l'apparition de satellites autour des reflexions fondamentales. Ces deux fonctions, remarquablement definies a longue distance dans les echantillons soigneusement traites, peuvent, dans certaines conditions, etre evaluees independamment l'une de l'autre. Nous observons que l'amelioration du degre d'ordre accentue la 'modulation de position'. Dans le cas des alliages hors-stoechiometrie, l'exces d'or (alliages riches en or) est distribue statistiquement dans tout le volume alors que l'exces de cuivre (alliages riches en cuivre) se repartit preferentiellement au voisinage des frontieres d'antiphase. (auteur)}
place = {France}
year = {1965}
month = {Jul}
}