Mechanically driven phase transformation from crystal to glass in Ti-Al binary system
- Academia Sinica, Shenyang (China). National Key Lab for RSA
Metastable phases such as metallic glass have been widely studied during the past few years. A number of techniques have been employed to synthesize these alloys, among which, mechanical alloying (MA) was considered to be a promising tool for large production and economical operation. However, the mechanism of formation of the metastable phases during mechanical alloying/ball milling have not been well determined. Previous studies of amorphization by mechanical alloying of pure elements or ball milling of intermetallics have proposed the following mechanics: rapid quenching of local melts produced by mechanical impacts, high density of defects generated by mechanical deformation which raises the free energy of compound to above that of the amorphous phase, effective local temperature rise at the collision site which gives rise to a solid-state reaction similar to thin film diffusion couples. Most of the studies have suggested that solid-state-type reactions are most likely to be responsible for vitrification during mechanical alloying, and the kinetics was controlled by the point and lattice defects generated by mechanical deformation. In the Zr-Al alloy system, however, another mechanisms was proposed by Fecht et al. based on a chemically induced catastrophic transition. The amorphization was interpreted with the elastic instability of crystal caused by the atomic mismatch of two components in supersaturated solid solution; when solute concentration reaches a critical value, the supersaturated solid solution becomes metastable and a polymorphous melting'' transition to a glass may occur. This hypothesis has been further examined by Ma and Atzmon with calorimeter measurements. In this paper, it will be shown experimentally that this mechanism may be valid in the Ti-Al binary system.
- OSTI ID:
- 6550239
- Journal Information:
- Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 32:2; ISSN 0956-716X; ISSN SCRMEX
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101 -- Metals & Alloys-- Preparation & Fabrication
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
AMORPHOUS STATE
BINARY ALLOY SYSTEMS
CRYSTAL-PHASE TRANSFORMATIONS
DATA
EXPERIMENTAL DATA
INFORMATION
MACHINING
MILLING
NUMERICAL DATA
PHASE TRANSFORMATIONS
TITANIUM ALLOYS