IngentaConnect The Platinum Development Initiative: Platinum-Based Alloys for Hi...

Authors: Douglas, A.; Hill, P.J.; Murakumo, T.; Cornish, L.A.; Süss, R.

Source: Platinum Metals Review, Volume 53, Number 2, April 2009 , pp. 69-77(9)

Abstract:

Under the Platinum Development Initiative, platinum-based alloys were being developed for high-temperature and special applications requiring good corrosion and oxidation resistance. Work on ternary alloys had previously identified that the best of these alloys for both mechanical properties and oxidation resistance were Pt-Al-Cr and Pt-Al-Ru, as reported in Part I of the present series (1). This paper (Part II) describes transmission electron microscopy work undertaken on a range of ternary alloys to understand the strengthening mechanisms of the alloys, ascertain the nature of the ∼ Pt₃Al precipitates and deduce the misfits between the precipitates and the matrix. A binary Pt-Al alloy was also studied in an attempt to resolve the two different versions of the phase diagram. A modified D0′_c tetragonal version of one of the lower temperature forms of ∼ Pt₃Al was discovered. The transformation producing the D0′_c structure was confirmed as displacive, since there were distinct bands in the precipitates, which were identified as twins at higher magnifications. The dislocation interactions were also studied, and found to be more complex than nickel-based superalloys, mostly due to the different precipitate types.

The Platinum Development Initiative: Platinum-Based Alloys for High Temperature and Special Applications: Part II