The behaviour of PT-based alloys at high temperature
Date
2009-03-27T10:00:03Z
Authors
Tshawe, Wendy
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Abstract
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
Description
Keywords
Pt-based alloys, Aluminium, Pt platinum, Phase diagrams