Determination of the activation energy in a cast aluminium alloy by TEM and DSC

The precipitation behaviour and microstructure development of the A319 alloy during ageing were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM and STEM). During T5 treatment, θ′ precipitates with an average size of about 18 nm were observed by TEM. The prec...

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Bibliographic Details
Published in:	Journal of alloys and compounds Vol. 432; no. 1; pp. 241 - 246
Main Authors:	Ovono Ovono, D., Guillot, I., Massinon, D.
Format:	Journal Article
Language:	English
Published:	Lausanne Elsevier B.V 25-04-2007 Elsevier
Subjects:	Activation energy Cross-disciplinary physics: materials science; rheology Exact sciences and technology Intermetallics Materials science Microstructure Phase diagrams and microstructures developed by solidification and solid-solid phase transformations Physics Precipitation Precipitation kinetics Intermetallics Precipitation kinetics Microstructure Activation energy Differential scanning calorimetry Scanning electron microscopy Particle size Intermetallic compounds Heat treatments Cast alloy Precipitation Transmission electron microscopy Aluminium alloys Arrhenius equation Aging Kinetics Diffusion Scanning transmission electron microscopy
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Summary:	The precipitation behaviour and microstructure development of the A319 alloy during ageing were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM and STEM). During T5 treatment, θ′ precipitates with an average size of about 18 nm were observed by TEM. The precipitate sizes increased with ageing temperature and attained an average size of 107 nm. In addition, there was a linear relationship between precipitate growth temperature and the cube of the precipitate size. This indicates that precipitate growth of the A319 alloy belongs to a thermal activated process of the Arrhenius type. The activation energy for the precipitate growth was calculated to be 140.4 ± 13.3 kJ/mol. However, under continuous heating conditions, the activation energy for the precipitate growth obtained by Kissinger plot was determined to be 119.5 ± 8.3 kJ/mol. Allowing for experimental error, both values are comparable and are related to the diffusion of Cu and/or Si in Al.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23
ISSN:	0925-8388 1873-4669
DOI:	10.1016/j.jallcom.2006.05.132