Cooling and heating rate dependence of precipitation in an Al-Cu alloy
Cooling and heating rate dependence of precipitation in an Al-Cu alloy
Differential scanning calorimetry and X-ray diffraction were used to study the cooling and heating rate dependence of precipitation in an Al-1.66 at.% Cu alloy. After homogenizing, cooling at a rate of 22 K min?1 (SC22) is sufficient to retain all copper in solid solution. GP-zone formation during subsequent heat treatment is hindered; this is ascribed to an insufficient number of (excess) vacancies. After a water quench (WQ) a large number of GP zones are formed during subsequent storage at room temperature for 1 h. The heat content of the GP-zone dissolution effect can quantitatively be described in terms of the heat of precipitation of GP I zones and the solid solubilities as derived from the GP I zone solvus. The heat content of the combined ??-/?-phase precipitation effect appeared to be proportional to the number of copper atoms precipitated, yielding an average value for the heat of copper precipitation of 36 kJ mol?1 copper. The activation energy for ??-phase formation is 0.75 eV for SC22 specimens and 1.10 ± 0.10 eV for WQ specimens. The differences in reported activation energies for ??-phase formation are discussed in terms of mobility of dissolve atoms (related to the vacancy concentration), interfacial energy and direction of growth (normal or perpendicular to the ??-phase plate).
183-194
Starink, M.J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
van Mourik, P.
47b86384-abdc-4cef-9e8f-a9d5bd86f12d
15 August 1992
Starink, M.J.
fe61a323-4e0c-49c7-91f0-4450e1ec1e51
van Mourik, P.
47b86384-abdc-4cef-9e8f-a9d5bd86f12d
Starink, M.J. and van Mourik, P.
(1992)
Cooling and heating rate dependence of precipitation in an Al-Cu alloy.
Materials Science and Engineering: A, 156 (2), .
(doi:10.1016/0921-5093(92)90150-Y).
Abstract
Differential scanning calorimetry and X-ray diffraction were used to study the cooling and heating rate dependence of precipitation in an Al-1.66 at.% Cu alloy. After homogenizing, cooling at a rate of 22 K min?1 (SC22) is sufficient to retain all copper in solid solution. GP-zone formation during subsequent heat treatment is hindered; this is ascribed to an insufficient number of (excess) vacancies. After a water quench (WQ) a large number of GP zones are formed during subsequent storage at room temperature for 1 h. The heat content of the GP-zone dissolution effect can quantitatively be described in terms of the heat of precipitation of GP I zones and the solid solubilities as derived from the GP I zone solvus. The heat content of the combined ??-/?-phase precipitation effect appeared to be proportional to the number of copper atoms precipitated, yielding an average value for the heat of copper precipitation of 36 kJ mol?1 copper. The activation energy for ??-phase formation is 0.75 eV for SC22 specimens and 1.10 ± 0.10 eV for WQ specimens. The differences in reported activation energies for ??-phase formation are discussed in terms of mobility of dissolve atoms (related to the vacancy concentration), interfacial energy and direction of growth (normal or perpendicular to the ??-phase plate).
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Published date: 15 August 1992
Organisations:
Engineering Mats & Surface Engineerg Gp
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Local EPrints ID: 375705
URI: http://eprints.soton.ac.uk/id/eprint/375705
ISSN: 0921-5093
PURE UUID: 0baff1d1-db8d-4414-957a-64b9abbe7c7c
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Date deposited: 13 Apr 2015 09:17
Last modified: 14 Mar 2024 19:30
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P. van Mourik
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