Neutron and x-ray studies of TiAl-Nb intermetallics undergone high-pressure torsion
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Date
2016-11-29
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Publisher
Australian Institute of Nuclear Science and Engineering
Abstract
High-pressure torsion is a severe-plastic-deformation technique rendering the bulk metallic material into an ultrafine microstructure. Not only the application of high pressure in the 6 GPa range bears potential for phase transformation, moreover huge plastic shear strains of 10 to 100 is achieved by torsion processing. In a first study, pellets of y-based Ti-45Al-7.5Nb have been processed under 6 GPa at room temperature, (i) with pressure loading and unloading only, (ii) with 5 turns of torsion and (ii) 10 turns. The material, which usually is
brittle and hard to deform, was successfully processed and showed ductility under these conditions. First investigations by neutron and X-ray diffraction are presented, emphasizing the complementarity of both kinds of quantum beams. While X-rays determine the overall structure, such as close-packing, neutrons are particularly sensitive to the order parameter in the constituting y-TiAl and a2-Ti3Al intermetallic phases. It is found that the atomic order decreases on larger amount of processing. Also structural transformations regarding the
atomic packing take place. These preliminary examinations open routes for physical understanding and recovery of the occurring crystallographic transformation and microstructural arrangements.
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Keywords
Pressure range mega pa 10-100, Torsion, Deformation, Phase transformations, Ductility, X-ray diffraction, Neutron diffraction, Intermetallic compounds, Microstructure, Crystallography
Citation
Li, X., Dippenaar, R., Kawasaki, M., & Liss, K.-D. (2016). Neutron and x-ray studies of TiAl-Nb intermetallics undergone high-pressure torsion. Paper presented at 13th AINSE-ANBUG Neutron Scattering Symposium, Sydney, NSW, Australia, 29-30 November 2016.