Oxidation of a conventionally cast Cantor high entropy alloy in an argon flow during creep tests at high temperature

Abstract

A conventionally cast version of the Cantor alloy (equimolar in Co, Ni Fe, Mn and Cr) was elaborated and samples were cut to carry out three points flexural creep tests according to a (1000, 1050, 1100°C)  (10, 20 and 30 MPa) array to explore the possibility of use in term of temperature and stress. For a majority of cases the deformation rates were too high, revealing a lack of practical interest, except for 10 MPa for which, whatever the temperature tests longer than 100 hours were realized. These tests were all performed under a slow flow of argon o preserve the alloy from oxidation during the tests. In fact, oxygen present as impurity (about 10 ppm) induced a signification oxidation of the samples which were covered by complex oxides involving Mn and Cr in various proportions and for different stoichiometries for the oxygen importance point of view, with thickness not far from what can be obtained in synthetic air for similar conditions.