Diffusion behaviour of Pt in platinum aluminide coatings during thermal cycles

Abstract

Two-phase PtAl 2 +b-(Ni,Pt)Al and single-phase b-(Ni,Pt)Al coatings were fabricated on DD5 Ni-based superalloy and pure Ni substrates. A coating/pure Ni substrate system was studied to determine the diffusion behaviour of Pt in the Ni-Al-Pt ternary system. The evolutions of morphology, phases and component concentration during thermal cycles were analysed. It was found that there is a phase shift from PtAl 2 to b* in the two-phase coating, and Kirkendall porosity was observed in the single-phase coating. Our results further indicated that there are two different diffusion paths of Pt in the Ni-Al-Pt system.