Experimental and thermodynamic analysis of differences in phase transformation of Pt-modified nickel aluminide coating during isothermal and cyclic oxidation

Vladimir A. Esin (1) , Fabrice Gaslain (1)

1 MAT - Centre des Matériaux

Phase transformation of Pt-modified nickel aluminide coating β-(Ni,Pt)Al into γ′ phase was studied during isothermal and cyclic oxidation at 1100 °C. The transformation occurred with homogeneous β and γ′ phases with chemical compositions depending on oxidation conditions. Cyclic oxidation led to a higher volume fraction of topologically close-packed (TCP) phases formed in the interdiffusion zone and the chemical composition of TCP phases was found to vary with oxidation conditions. This difference in TCP precipitation in the interdiffusion zone for isothermal and cyclic oxidation was suggested to be responsible for different β and γ′ compositions. The experimental observations were discussed using thermodynamic calculations by Thermo-Calc software, and some explanations were given.

Mots clés: Pt-modified nickel aluminide coating; Oxidation; Phase transformation; Diffusion; Ni-base superalloy; Calphad

Domaines: Physique [physics]; Matière Condensée [cond-mat]; Science des matériaux [cond-mat.mtrl-sci]

Vladimir A. Esin, Fabrice Gaslain. Experimental and thermodynamic analysis of differences in phase transformation of Pt-modified nickel aluminide coating during isothermal and cyclic oxidation. Surface and Coatings Technology, 2016, 307, pp.915-925. ⟨10.1016/j.surfcoat.2016.10.014⟩. ⟨hal-01421908⟩