ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Stability of TCP phases in Co-based superalloys: comparison of ab initio results with structure maps

Date: 17.02.2014
Place: TMS Annual Meeting and Exhibition, San Diego, USA

Jörg Koßmann
Ralf Drautz
Thomas Hammerschmidt

We compare Co-based and Ni-based materials using high-throughput density-functional theory calculations. We investigate the stability and elastic properties of the γ’ phase in the ternary Co-Al-W system and compare to Ni-based compounds. The precipitation of topologically close-packed (TCP) phases deteriorates the mechanical properties of superalloys. In order to study the stability of such precipitates in Co-based superalloys, we determine the heat of formation of the typical TCP phases A15, C14, C15, C36, μ, χ, and σ in the Co-W, Al-W, and Co-Al binaries. We show that our DFT results are in line with a recently derived structure map based on experimental data and can be rationalised in terms of average band filling and atomic size differences. This work is part of the collaborative research center SFB/TR 103.

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