CoCrFeNiMo High Entropy Alloys Behavior in Superheated Geothermal Steam

Abstract

Equi-atomic high entropy alloys (EHEA) are a class of materials exhibiting tremendous properties due to the four characteristics effect: high entropy, sluggish diffusion, lattice distortion and cocktail effect. CoCrFeNiMo composition was tested in situ, at Reykjanes power plant and the results revealed a very low corrosion rate for the bulk material. The most effective way to protect components interacting directly to geothermal steam would be coating the parts with EHEA, CoCrFeNiMo. This paper presents the behavior in simulated superheated geothermal steam of bulk sample of CoCrFeNiMo and a carbon steel sample coated with a thin CoCrFeNiMo layer. The bulk samples were prepared using vacuum arc remelting technique and the coated samples were realized using electro-spark deposition with an electrode manufactured from the bulk sample of CoCrFeNiMo. The exposure was produced in the reactor present in University of Iceland, in simulated superheated geothermal environment. The corrosion rate was calculated and the samples were investigated using optical and scanning electron microscope and X rays diffractometer. The investigation of the samples revealed interesting results for the CoCrFeNiMo in superheated geothermal steam.