High temperature precipitation kinetics and ttt curve of a 7xxx alloy by in-situ electrical resistivity measurements and differential calorimetry

In this study, we have developed a very sensitive in situ resistivity measurement method to determine the high temperature precipitation kinetics in aluminum alloys. This method has been validated in the case of linear cooling rates with differential scanning calorimetry experiments. This comparison...

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Bibliographic Details
Published in:Scripta materialia 2000-03, Vol.42 (7), p.675-680
Main Authors: Archambault, Pierre, Godard, David
Format: Article
Language:English
Subjects:
ALUMINIUM BASE ALLOYS
Aluminum alloys
Applied sciences
CALORIMETRY
Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
Cross-disciplinary physics: materials science
rheology
DTA
ELECTRIC CONDUCTIVITY
Exact sciences and technology
KINETICS
MATERIALS SCIENCE
Metals. Metallurgy
Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
PHASE STUDIES
Phase transformations
Physics
PRECIPITATION
Quench cooling
QUENCHING
Resistivity
SOLID SOLUTIONS
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Summary:In this study, we have developed a very sensitive in situ resistivity measurement method to determine the high temperature precipitation kinetics in aluminum alloys. This method has been validated in the case of linear cooling rates with differential scanning calorimetry experiments. This comparison has shown that > 200 deg C the different precipitation processes observed by Differential Scanning Calorimetry (DSC) are revealed as a single process by the resisitivity measurement which reinforces the validity of the Mathiessen's rule in this temperature range. Work was extended to interrupted quenching (from the solutionizing temperature) and isothermal holdings. Using the differential resistivity curves, we have determined the isothermal kinetics and a Time-Temperature-Transformation (TTT) curve for the precipitation of the M phase. Iso-precipitated fraction curves have then been linked and qualititively compared to Time-Temperature-Properties (TTP) curves. A local scale characterization of the precipitation is now under work to precise the microstructural processes related to some resistivity deviation, especailly < 200 deg C. Results will be presented elsewhere. Alloy: 7010.
ISSN:1359-6462
1872-8456
DOI:10.1016/S1359-6462(99)00419-4