Numéro |
J. Phys. IV France
Volume 124, Mai 2005
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Page(s) | 9 - 15 | |
DOI | https://doi.org/10.1051/jp4:2005124002 |
J. Phys. IV France 124 (2005) 9-15
DOI: 10.1051/jp4:2005124002
The effects of milling conditions on the subsequent oxidation behaviour of mechanically alloyed FeAl-based powders
J. Ritherdon1, H. Al-Badairy1, A.R. Jones1, G.J. Tatlock1 and I.G. Wright21 Department of Engineering, University of Liverpool, Liverpool L69 3GH, UK
2 Oak Ridge National Laboratory, Oak Ridge, Tennessee, TN37831, USA
Abstract
Mechanically alloyed, Fe3Al-based, oxide dispersion
strengthened alloys form a surface oxide scale during powder processing.
This scale becomes entrained in the consolidated alloy, and may have a
significant effect on subsequent recrystallisation behaviour. The high
oxidation rates found in these alloys are mainly due to the bulk alloy
composition. However, batch-to-batch differences in oxidation mass gain
occur in powders with ostensibly identical compositions. Batches PMWY2 and
PMWY3 were studied and parameters such as alloy composition and homogeneity,
powder surface area to volume ratios and scale thickening rates considered.
Batch PMWY2 showed 20-90% faster weight gain than PMWY3 and reached the
onset of breakaway oxidation approximately twice as quickly. PMWY2 was found
to contain aluminium-depleted regions, whereas PMWY3 is much more
homogeneous. The surface area to volume ratio for PMWY2 was 44% higher
than that of PMWY3, and batch PMWY2 was found to contain extremely fine
powder particles. The scale on batch PMWY2 thickened more quickly than that
on batch PMWY3, with rates 20-40% higher at different stages in the
oxidation. The major contributory factor to the difference in oxidation mass
gain between the two alloy batches is scale thickening rate and factors
influencing thickening rates are discussed.
Key words: Fe3Al powder, oxidation, mass gain, mechanical alloying, inhomogeneity.
© EDP Sciences 2005