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Original title:
Impact of Heat Treatment Environment of Microstructure and Transformation Path in NiTi Shape Memory Alloy
Authors: Kuběnová, Monika ; Zálešák, Jakub ; Čermák, Jiří ; Barták, Tomáš ; Dlouhý, Antonín
Document type: Papers
Conference/Event: METAL 2011 /20./, Brno (CZ), 2011-05-18 / 2011-05-20
Year: 2011
Language: eng
Abstract: We report results of differential scanning calorimetry (DSC) experiments in which heat flow (T) from and to Ti-50.9at%Ni shape memory samples was recorded during the temperature scan through a B2 B19’ transformation range. Prior to the DSC experiments, the samples were separately annealed in evacuated quartz capsules containing different hydrogen and helium mixtures with an overall filling pressure of 900 mbar. The quartz tubes containing the annealed samples were subsequently quenched into cold water. After quenching, the capsules were opened, martensitic transformations were investigated by DSC and the microstructure of the samples was assessed by transmission electron microscopy (TEM). Annealing in the mixtures with an increasing partial pressure of hydrogen led to a considerable drop in the latent heat associated with the B2 B19’ martensitic transformation. Results obtained using TEM suggest that hydrogen may function as a catalytic substance that accelerates the long range ordering of Ni atoms in early stages of Ni4Ti3-phase precipitation. The selected area diffraction study focused on patterns in <100>B2 and <110>B2 zones and provided evidence for diffuse scattering due to spatial modulations of the lattice constant. These variations in the background electron intensities might be related to a precursor of Ni4Ti3 phase in its early state of formation.
Keywords: heat flow; heat treatment atmosphere; nickel-rich NiTi shape memory alloys
Project no.: CEZ:AV0Z20410507 (CEP), GA106/09/1913 (CEP)
Funding provider: GA ČR
Host item entry: METAL 2011 Conference Proceedings, ISBN 978-80-87294-22-2
Institution: Institute of Physics of Materials AS ČR (web)
Document availability information: Fulltext is available at the institute of the Academy of Sciences.
Original record: http://hdl.handle.net/11104/0006938
Permalink: http://www.nusl.cz/ntk/nusl-110453
The record appears in these collections:
Research > Institutes ASCR > Institute of Physics of Materials
Conference materials > Papers
Authors: Kuběnová, Monika ; Zálešák, Jakub ; Čermák, Jiří ; Barták, Tomáš ; Dlouhý, Antonín
Document type: Papers
Conference/Event: METAL 2011 /20./, Brno (CZ), 2011-05-18 / 2011-05-20
Year: 2011
Language: eng
Abstract: We report results of differential scanning calorimetry (DSC) experiments in which heat flow (T) from and to Ti-50.9at%Ni shape memory samples was recorded during the temperature scan through a B2 B19’ transformation range. Prior to the DSC experiments, the samples were separately annealed in evacuated quartz capsules containing different hydrogen and helium mixtures with an overall filling pressure of 900 mbar. The quartz tubes containing the annealed samples were subsequently quenched into cold water. After quenching, the capsules were opened, martensitic transformations were investigated by DSC and the microstructure of the samples was assessed by transmission electron microscopy (TEM). Annealing in the mixtures with an increasing partial pressure of hydrogen led to a considerable drop in the latent heat associated with the B2 B19’ martensitic transformation. Results obtained using TEM suggest that hydrogen may function as a catalytic substance that accelerates the long range ordering of Ni atoms in early stages of Ni4Ti3-phase precipitation. The selected area diffraction study focused on patterns in <100>B2 and <110>B2 zones and provided evidence for diffuse scattering due to spatial modulations of the lattice constant. These variations in the background electron intensities might be related to a precursor of Ni4Ti3 phase in its early state of formation.
Keywords: heat flow; heat treatment atmosphere; nickel-rich NiTi shape memory alloys
Project no.: CEZ:AV0Z20410507 (CEP), GA106/09/1913 (CEP)
Funding provider: GA ČR
Host item entry: METAL 2011 Conference Proceedings, ISBN 978-80-87294-22-2
Institution: Institute of Physics of Materials AS ČR (web)
Document availability information: Fulltext is available at the institute of the Academy of Sciences.
Original record: http://hdl.handle.net/11104/0006938
Permalink: http://www.nusl.cz/ntk/nusl-110453
The record appears in these collections:
Research > Institutes ASCR > Institute of Physics of Materials
Conference materials > Papers
Record created 2012-04-03, last modified 2024-01-26