Phase transformations in the Nb-Au system by ball milling and the study of the metastable phases

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(93)90106-3· OSTI ID:6223353

Di, L M; Bakker, H ^[1]; Barczy, P; Gacsi, Z ^[2]

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1. Univ. van Amsterdam, Valckenierstraat (Netherlands). Van der Waals-Zeeman Lab.
2. Univ. of Miskolc (Hungary). Dept. of Physical Metallurgy

A detailed study on the Nb-Au binary alloy system upon ball milling is reported. An analysis of the energy levels of the Nb-Au alloy reveals that the solid solution has a lower enthalpy than the amorphous state for all compositions. The ball milling experiments were performed on five compositions of the Nb-Au alloys. All five alloys transformed to solid solutions after 40 h of grinding. The structures of these solid solutions are different depending on the composition of the starting material. In further experiments, the properties of the metastable phases obtained by ball milling were studied. The lattice parameter of the solid solutions turns out to obey Vegard's law. The exothermic heat of the phase restoration appears to be approximately proportional to the enthalpy as predicted by Miedema's semi-empirical model. The magnitude of the peak temperatures and the activation energies follows the same trend as the melting temperatures. Examination of particle size and shape for two compositions gives more insight in the milling process. Finally, the results for prolonged milling are presented.

• OSTI ID: 6223353
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 41:10; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
AMORPHOUS STATE
BINARY ALLOY SYSTEMS
ENTHALPY
GOLD ALLOYS
INTERMETALLIC COMPOUNDS
MACHINING
MILLING
NIOBIUM ALLOYS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES