High temperature oxidation of non equi-atomic Al5Cr12Fe35Mn28Ni20high entropy alloy

Abstract

The Oxidation behavior of the Al5Cr12Fe35Mn28Ni20 high entropy alloy was investigated in air at temperatures 900 °C, 1000 °C and 1100 °C for 100 h isothermally. The oxidation kinetics at all temperatures obeys the parabolic rate law with an activation energy 100.6 kJ mol-1. The alloy was externally oxidized forming duplex layer consisted of manganese oxides that overlays Mn-Cr-Fe spinel oxides. While, it was observed that at 1000 °C and 1100 °C the samples were also oxidized internally forming Al2O3 deep in the alloy. The initial oxidation behavior of the alloy oxidized at 1000 °C for 1 and 24 h producing external scale of Mn3O4 overlaying Mn-Cr-Fe spinel oxide and Al2O3 precipitates.