Previously published work on the development of the Pt-based superalloys for high
temperature and special applications, as well as phase equilibria work, showed that there
were problems and uncertainties with the available Pt-Al phase diagram.
The aim of the current work was to make a comprehensive study of all relevant phases, and
to clarify the phase boundaries of the phases: (Pt), Pt3Al (all temperature versions), Pt2Al
(both phases), and Pt5Al3, by use of higher resolution SEM and XRD.
A displacive transformation was confirmed for cubic Pt3Al to tetragonal Pt3Al and from
high temperature Pt2Al to low temperature Pt2Al. The -phase was observed to be present,
the phase reactions were confirmed and the eutectic composition was found. The Pt6Al21
phase was identified instead of Pt5Al21, and was deduced to be a different interpretation of
the same phase, although the former had been described as a metastable phase. The phases
and phase boundaries were found to generally agree with Massalski, and disagreed with Oya
et al. ’s phase diagram
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/6828 |
| Date | 27 March 2009 |
| Creators | Tshawe, Wendy |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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