Manufacturing Technology 2023, 23(2):247-253 | DOI: 10.21062/mft.2023.016

Influence of the Mn Content on the Corrosion Behaviour of HEA CoCrFeN-iMnX (X=5, 20, 35 at.%) Prepared via MA+SPS

Filip Průša ORCID...¹, Petr Kratochvíl ORCID...¹, Hana Thürlová ORCID...¹, Darya Rudomilova ORCID...², Šárka Msallamová ORCID...¹

¹ University of Chemistry and Technology Prague, Department of Metals and Corrosion Engineering Technická 5, 166 28 Prague 6, Czech Republic

² Technopark Kralupy, University of Chemistry and Technology Prague, 166 28 Prague, Czech Republic

The high entropy alloys with intended chemical compositions of CoCrFeNiMnX (X=5, 20 and 35 at.%) were prepared by the means of mechanical alloying. Prepared powders were then compacted using the progressive spark plasma sintering, which minimizes the deleterious microstructural coarsening. The compacts were, regardless of the actual chemical composition, composed of a solid solution with FCC crystallographic lattice and a small amount of carbides identified as Cr7C3. The dimensions of those carbides increased with the content of Mn, which was confirmed also by atomic force microscopy (AFM) and scanning kelvin probe microscopy (SKPM). The surface topography measured by AFM confirmed its presence as they emerged from the surface, perfectly matching the positive potential measured by the SKPM. It was found, that the HEAs are showing rather worse corrosion resistance in the aqueous environment containing 9 g/l NaCl compared to the reference 316L stainless steel. Moreover, the higher the content of Mn, the worse the corrosion resistance increasing the corrosion current density and shifting open circuit potential towards more negative values. When exposed to the elevated temperature of 600 °C, the alloys formed a poor protective oxidic layer that tended to chip off due to thermal stresses.

Keywords: High entropy alloys, mechanical alloying, spark plasma sintering, potentiodynamic measurements, properties.

Grants and funding:

This research was financially supported by Czech Science Foundation (grant No. 21-11313S)

Received: January 18, 2023; Revised: January 18, 2023; Accepted: April 11, 2023; Prepublished online: April 25, 2023; Published: May 4, 2023  Show citation