Creep and Magnetism of the CoCrFeNiMn High Entropy Alloy

An equiatomic quinary alloy, CoCrFeMnNi, which crystallizes as a single FCC phase and exhibits apparent thermodynamic stability in a wide temperature range [1], has been investigated as a model for high configurational entropy system. Understanding creep in such compositionally complex alloys is important because controversies still exist concerning their classification into Class I and Class II creep behaviours [2]. Tensile and compression creep tests were performed at temperatures between 873 and 1073 K in a range of applied stresses. Microstructures were investigated using advanced SEM and TEM techniques. Results suggest that the Cantor alloy obeys a phenomenological Norton law with the stress exponent n=3 and thus exhibits a Class I creep behaviour in a wide range of external conditions. These macroscopic characteristics and the associated microstructural evolution are discussed in a light of current creep models.

In the second part, we present first ever experimental data on magnetic transitions in the investigated quinary system. A cooling below about 90 K freezes magnetic moments carried by individual atoms in a spin-glass state. A second magnetic transition of a ferromagnetic type is detected at 40 K. A field-assisted cooling into the temperature regime below 40 K results in a systematic vertical shift of hysteresis curves. This interesting new phenomenon is attributed to stable configurations that local magnetic moments form in the first co-ordination group of Mn atoms.


1. F. Otto et al., Acta Mater. 61, pp. 5743 - 5755 (2013).

2. O. D. Sherry and P. M. Burke, Prog. Mat. Sci. 13, 323 - 390 (1968).

Acknowledgement. This research was supported by CSF under the contract no. 14-22834S and by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division (alloy preparation).



Institute of Physics of Materials, Academy of Sciences of the Czech Republic

Thursday, November 16, 2017 - 15:00
Prof. Antonín Dlouhý