AlN-Assisted Internal Oxidation Behavior in an Al-Containing High Mn Steel

Abstract

The role of AlN on the internal oxidation behavior was investigated in an Al-containing high Mn steel. The sequential formation of internal oxidation and AlN+γ-matrix layers on the γ-matrix was observed using an EPMA, an SEM, and a TEM after the heat-treatment in air. The heterogeneous nucleation of MnAl2O4 on the AlN was identified in between the internal oxidation and AlN+γ-matrix layers. MnAl2O4 shows the [2-1-10]AlN//[110]MnAl2O4 and (0002)AlN//(-11-1)MnAl2O4 orientation relationship with the pre-existing AlN by sharing Al atoms. The coherency between MnAl2O4 and AlN and the evolution of oxides in an Al-containing high Mn steel were further discussed.