ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Comparing Co-based and Ni-based superalloys with density-functional theory

Date: 16.07.2015
Place: Departmental Lunch Colloquium of the Department of Materials Science and Engineering, Delft University of Technology, Delft, The Netherlands

Jörg Koßmann
Thomas Hammerschmidt
Ralf Drautz

Single crystal superalloys are used widely in high-temperature applications. Most commercial superalloys are based on Ni-Al and comprise 10 or more alloying elements. For example, Re and other 5d elements are added to improve creep resistance. Recently, materials based on Co-Al-W were shown to exhibit a γ/γ' microstructure which makes these alloys interesting for singe crystal superalloy applications.

We compare and contrast Co-based and Ni-based alloys by high-throughput densityfunctional theory (DFT) calculations. We relate phase stabilities in Co-X and Ni-X binary systems with X=Al, W, Re and the ternary systems Co-Al-W and Ni-Al-Re. Our DFT results are also used in ab initio CALPHAD calculations. Furthermore, we use a newly parameterised cluster expansion in order to study the solubility of the transition elements W, Mo, Ti, and Ta on the Al sublattice of L12-Co3Al.

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