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MM: Fachverband Metall- und Materialphysik
MM 12: Transport - High Entropy Alloys
MM 12.2: Vortrag
Montag, 16. März 2020, 16:00–16:15, IFW A
tracer diffusion in the σ-phase of the CoCrFeMnNi system — jingfeng zhang1, mohan muralikrishna garlapati1,2, alex asabre3, guillaume laplanche3, sergiy divinski1, and •gerhard wilde1 — 1Institute of Materials Physics, University of Münster, Münster, Germany — 2Department of Metallurgical & Materials Engineering, Indian Institute of Technology Madras, Chennai, India — 3Institut für Werkstoffe, Ruhr-Universität Bochum, Bochum, Germany
Formation of a Cr-rich σ-phase in the CoCrFeMnNi high-entropy alloy during long term exposures at intermediate temperatures (< 1073 K) is detrimental for the mechanical properties. The σ-phase represents a topologically close-packed complex phase with a tetragonal structure. The diffusion processes which take place in the σ-phase are very important to understand the kinetics of precipitation of this phase in the cantor alloy. So far, there are no reports on diffusion in the σ-phase composed of elements in Cantor alloys.
In the present work, the σ-phase with the composition Co46Cr15.2Fe16.3Mn17Ni5.5 (in at.%) was produced and investigated. For the first time, tracer diffusion of Ni and Fe was measured in the temperature interval from 928 - 1173 K using 64Ni and 58Fe natural isotopes in combination with depth profiling by a secondary ion mass spectroscopy. Diffusion of both Ni and Fe in the σ-phase is found to be faster compared to that in the Cantor alloy. Various reasons influencing diffusion in the σ-phase and its effect on phase stability of the Cantor alloy system are discussed.