Contribution to the Study of the Niobium-Aluminum System; CONTRIBUTION A L'ETUDE DU SYSTEME NIOBIUM/ALUMINIUM
Alloys covering the entire range of composition between pure Al and pure Nb were prepared by argon-arc melting using a non-consumable tungsten electrode. It was, however, not possible to prepare alloys containing a high percentage of Nb (over 40 at.%) directly from the two pure metals, and it was found necessary to start from Nb and a parent alloy containing about 47 wt% Al (corresponding roughly to the compound NbAl/sub 3/). This method made it possible to achieve a considerable reduction in the Al losses resulting from volatilization in the course of the melting process. The alloys were heat-treated in a tantalum resistance furnace up to 1800 nif- C. This furnace makes it possible to quench the sample in vacuo in a liquid metal bath. The Al losses resulting from surface evaporation were reduced by means of a special preparation of the sample before the vacuum treatment. Metallographic and radiocrystallographic examinations were carried out on the alloys. A dilatometric method was devised for the rapid determination of the solidus temperature in the Al-rich region; the use of this method was made possible by means of a high sensitivity, instant- reading electrical inductivetrap dilatometer. The eutectic NbAl/sub 3/--Al reaction and the eutectic reaction between the compounds NbAl/sub 3/ and Nb/sub 2/ Al were confirmed. It was possible to identify the Nb/sub 2/Al and Nb/sub 3/Al phases in the Nb-rich region. The equilibrium of the phases in this region was, however, found to be more complicated than reported in previous publications, since it must in particular account for solid-state transformations in the intermetallic compounds. (auth)
- Research Organization:
- European Atomic Energy Community; and Brussels. Centre d'Etude de l'Energie Nucleaire
- NSA Number:
- NSA-17-018743
- OSTI ID:
- 4709983
- Report Number(s):
- EUR-132.f
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINUM ALLOYS
ARGON
CRYSTALS
ELECTRIC ARCS
ELECTRIC CONDUCTIVITY
ELECTRODES
EUTECTICS
EVAPORATION
EXPANSION
FURNACES
HEAT TREATMENTS
HIGH TEMPERATURE
INTERMETALLIC COMPOUNDS
LIQUID METALS
MELTING
METALLOGRAPHY
METALS, CERAMICS, AND OTHER MATERIALS
NIOBIUM ALLOYS
PHASE DIAGRAMS
PREPARATION
QUANTITATIVE ANALYSIS
REACTION KINETICS
SURFACES
TANTALUM
TUNGSTEN
VACUUM