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Abstract
The central objective of this research was to assess the effects of temperature and particle size on the spark plasma sintering (SPS) response of two prealloyed aluminium powders atomised from wrought alloys AA 2024 and AA 7075. A SPS temperature of 400°C was found to yield fully dense specimens of both alloys with hardness values that were comparable to the starting wrought ingot materials. Such samples also exhibited appreciably lower concentrations of residual oxygen and hydrogen when compared to those present in the raw powders. Degassing experiments completed through thermogravimetric analyser (TGA)–gas chromatography (GC)–mass spectrometry (MS) indicated that the release of CO2 and adsorbed/chemisorbed H2O were responsible for the enhanced purity of the SPS products. Particle size was also a factor of influence with the most favourable results for density and minimised O/H concentrations achieved with particles ≧180 μm in diameter.
Acknowledgements
The authors would like to acknowledge the financial support provided by Boeing Research and Technology (contract 11-6392) and the Natural Sciences and Engineering Research Council of Canada (NSERC) (collaborative research and development grant no. 451466 and the post graduate scholarship awarded to lead author Chua). Technical discussions provided by researchers at Boeing (Dr R. Glamm, Dr S. Gaydos) and GKN Sinter Metals (I. Donaldson) are also acknowledged as are the laboratory support efforts provided by the PM research groups at Dalhousie University (G. Sweet, R. Cooke, J. O’Flynn, C. Whitman) and McGill University (J. Milligan).
