Atomistic insights into milling mechanisms in an Fe-Y2O3 model alloy

This experimental study combined with first principles modeling focuses on the distribution and behavior of yttria in pure iron powder particles prepared by mechanical alloying. A profound verification of the mechanism during milling is still missing in literature. Atom probe tomography and X-ray photoelectron spectroscopy measurements directly after mechanical alloying revealed yttria dissolved in the iron matrix, which later rearranged in clusters. These findings are corroborated by ab initio calculations demonstrating that the formation energy for Y substitutional defect in bcc-Fe is significantly lower in the close neighborhood of vacancies. X-ray diffraction measurements revealed that mechanical alloying for at least 12 hours caused a dramatic decrease in domain size and an extraordinary increase of defect density.