Publications
Concentration-dependent atomic mobilities in FCC CoCrFeMnNi high-entropy alloys
D. Gaertner, K. Abrahams, J. Kottke, V. A. Esin, I. Steinbach, G. Wilde, S. V. Divinski.
Acta Materialia, 166, 357-370, (2019)
Abstract
The diffusion kinetics in a CoCrFeMnNi high entropy alloy is investigated by a
combined radiotracer-interdiffusion experiment applied to a pseudo-binary
Co15Cr20Fe20Mn20Ni25/
Co25Cr20Fe20Mn20Ni15 couple. As a result, the
composition-dependent tracer diffusion coefficients of Co, Cr, Fe and Mn are
determined. The elements are characterized by significantly different diffusion
rates, with Mn being the fastest element and Co being the slowest one.
The elements having originally equiatomic concentration through the diffusion
couple are found to reveal up-hill diffusion, especially Cr and Mn. The atomic
mobility of Co seems to follow a S-shaped concentration
dependence along the diffusion path. The experimentally measured kinetic data are checked against the
existing CALPHAD-type databases.
In order to ensure a consistent treatment of tracer and chemical diffusion a
generalized symmetrized continuum approach for multi-component interdiffusion is
proposed.
Both, tracer and chemical diffusion concentration profiles are simulated and
compared to the measurements. By using the measured tracer diffusion
coefficients the chemical profiles can be described, almost perfectly, including
up-hill diffusion.
Keyword(s): high-entropy alloys; CoCrFeMnNi; interdiffusion; radiotracer diffusion; pair-wise diffusion model; CALPHAD databases
DOI: 10.1016/j.actamat.2018.12.033
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