High temperature oxidation behavior of Cr-Mn-Fe-Co-Ni high entropy alloy

Abstract

This study examined the surface oxidation properties of Cr-Mn-Fe-Co-Ni high entropy alloy (HEA) at high temperatures (900 degrees C, 1000 degrees C, 1100 degrees C/24 h) in the 21%O-2 and 79%N-2 atmosphere. An initial observation of microstructures confirmed that they consisted of random FCC solid solution, and the average grain size was measured at 245.5 pm. High-temperature oxidation tests of the Cr-Mn-Fe-Co-Ni HEA showed that its weight gained by 1.76, 4.45, and 9.08 mg/cm(2) at 900 degrees C, 1000 degrees C, and 1100 degrees C, respectively, and all three temperature conditions represented typical parabolic curves. Observation of its surface found that Cr2O3 and Mn2O3 were main oxides on a specimen tested at 900 degrees C, while (Mn, Cr)(3)O-4 and Mn3O4 were mostly shown to be main oxides on a specimen tested at 1000 degrees C and 1100 degrees C, despite the presence of Cr2O3. The high-temperature oxidation behavior of Cr-Mn-Fe-Co-Ni HEAs was found to have been largely affected by Cr and Mn elements. The resultant kirkendall pore generation, change in the concentration of elements, internal oxidation and Mn2O3-o Mn3O4 transformation were found to affect the oxidation resistance of Cr-Mn-Fe-Co-Ni high entropy alloy.