TY - JOUR A1 - Esakkiraja, N. A1 - Vishwakarma, A. A1 - Makineni, S. K. A1 - Jayaram, V. A1 - Hickel, Tilmann A1 - Divinski, S. V. A1 - Paul, A. T1 - Diffusion-controlled growth and microstructural evolution between Pt and Pd containing B2-NiAl bondcoats and Ni-based single crystal superalloy N2 - Pt-modified NiAl bond coats are used to extend the lifetime of blades in gas turbine engine applications. However, they suffer from the growth of deleterious precipitates within the interdiffusion zone. Partial substitution of Pt by Pd is advantageous in reducing the interdiffusion zone thickness between the bond coat and the superalloy, providing comparable oxidation properties, and critically reducing the propensity to form brittle (Pt,Ni)Al2 precipitates. In this study, we utilize the pseudo-binary diffusion couple method to estimate the interdiffusion coefficients of Ni and Al in Pd, Pd-Pt and Pt-modified nickel aluminides. Additionally, the main and cross-interdiffusion coefficients are estimated in the ternary diffusion couples. The estimated diffusion coefficients in the ๐›ฝ-NiAl phase reflect on the thickness of the ๐›ฝ phase in the superalloy bond coat interdiffusion zone. Pd reduces the pseudo-binary interdiffusion coefficients of Niโ€“Al and also decreases the main and cross-ternary interdiffusion coefficients. This correlates with the reduction of the interdiffusion zone thickness by Pd. The diffusion process is strongly assisted by point defects in this phase. Ab initio-informed defect calculations are done to explain diffusion retardation in the presence of Pd (compared to Pt) with decreased defect concentrations. Furthermore, through in-depth microstructure characterization performed by electron probe micro analyser, transmission electron microscopy, and atom probe tomography, the presence of ๐œŽ, ๐‘… and ๐œ‡ phases as TCP precipitates in the interdiffusion zone are identified. The results give insights into the coatingsโ€™ diffusional properties that influence the service life of the product. KW - Interdiffusion KW - Bondcoat KW - Topologically close pack (TCP) phase KW - Transmission electron microscopy KW - Atom probe tomography PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618091 DO - https://doi.org/10.1016/j.actamat.2024.119687 SN - 1359-6454 VL - 266 SP - 1 EP - 14 PB - Elsevier CY - Amsterdam AN - OPUS4-61809 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -