Electronic-scale assessment of high-temperature oxidation mechanisms in a novel Fe-based alloy

The development of alloys with high antioxidation performance is limited by the ambiguous details of the oxidation mechanism. Here, based on the structures of internal oxides detected by high-resolution transmission electron microscopy, a hybrid method combining first-principles calculation, climb image nudged elastic band method and quasi-harmonic Debye model has been implemented to explain the oxidation mechanism with an emphasis on the origin of delamination and cracking. The results showed that the delamination of oxides corresponds to the acceleration of diffusion of Cr element caused by lamellar structures. The reduction in the cracking occurrence at high temperature mainly results from the smaller bulk modulus of oxides. Furthermore, the stronger chemical bonds promoted by lamellar structures also correspond to the higher cracking resistance.