Observation and modeling of α-NiPtAl and Kirkendall void formations during interdiffusion of a Pt coating with a γ-(Ni-13Al) alloy at high temperature

Autor: Pascal Fabrice Bilhe, Sarah Hamadi, Aurélie Rouaix-Vande Put, Daniel Monceau, Pauline Audigié, Andre Malie
Přispěvatelé: Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), SAFRAN (FRANCE), Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), SNECMA Châtellerault [Châtellerault], Safran Group
Rok vydání: 2014
Předmět:
Zdroj: Surface and Coatings Technology
Surface and Coatings Technology, Elsevier, 2014, 260, pp.9-16. ⟨10.1016/j.surfcoat.2014.08.083⟩
ISSN: 0257-8972
DOI: 10.1016/j.surfcoat.2014.08.083
Popis: International audience; During the last 15 years, Pt-rich γ–γ′ bond-coatings have been studied extensively for their corrosion and oxidation resistance, and as a lower cost alternative to β-(Ni,Pt)Al bond-coatings in thermal barrier coating systems. To optimize their fabrication and durability, it is essential to investigate their interdiffusion with Ni-based superalloys. This study reports on experimental results and modeling of the interdiffusion of the model Pt/γ-(Ni-13Al) alloy system. Pt coatings were deposited either by electroplating or by spark plasma sintering using a Pt foil. Heat treatments at 1100 °C for 15min to 10 hwere performed either in a high-temperature X-ray diffraction device under primary vacuum or in a furnace under argon secondary vacuum. The α-NiPtAl phase with L10 crystal structure formed very rapidly, implying fast uphill Al diffusion toward the surface. For Pt electroplating, α-phase transformed to γ′-(Ni,Pt)3Al after only 45 min–1 h at 1100 °C. The resulting two-phased γ–γ′ microstructure remained up to 10 h. When using a Pt foil coating, the continuous layer of α-NiPtAl phase disappeared after 10 h and the γ′-(Ni,Pt)3Al or γ-(Ni,Pt,Al) phase appeared, resulting in two different diffusion paths in the Ni–Pt–Al phase diagram. Voids also formed at the interdiffusion zone/substrate interface for both systems after 1 h or more. Composition analyses confirmed that voids were located at the Pt diffusion front corresponding to the Al-depleted zone. Experiments performed with the samples coated with a Pt foil confirmed that voids are due to a Kirkendall effect and not to the Pt deposition process. Numerical simulations including the cross-term diffusion coefficients in the diffusion flux equations reproduced the experimental concentration profiles for the γ-phased systems.
Databáze: OpenAIRE
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