First-principles calculation of the interaction of Mn with ZrO2 and its effect on the formation of ferrite in high-strength low-alloy steels

The interaction between ZrO2 and the steel matrix was investigated by examining a solid-state bonded sample made of these two materials. A manganese-depleted zone and a ferrite-rich layer close to the bond line were observed. The formation energy of MnZr3O8 was determined to be negative, indicating the possibility of MnZr3O8 formation. Both experimental results and first-principles calculations supported the occurrence of diffusion of Mn into ZrO2 and the formation of ferrite within the Mn-depleted zone in the vicinity of ZrO2.

Experimental results and the first-principle calculations revealed that the diffusion of Mn into ZrO2 stimulated the formation of ferrite. This is because ZrO2 has cation vacancies and can absorb Mn. Optical micrograph showing the formation of ferrite on the layer of ZrO2 in a steel-ZrO2 bonded specimen after austenitization at 1523 K for 600 s and isothermal heat treatment at 933 K for 60 s. The composition profile of Mn across ZrO2 layer was obtained by EPMA.Figure optionsDownload high-quality image (186 K)Download as PowerPoint slide