Identification of oxide phases in oxide dispersion strengthened PM2000 steel

Abstract

The oxide phases in oxide dispersion strengthened PM2000 steel have been investigated by transmission electron microscopes. Two nano-sized yttrium aluminum oxide phases, YAlO3 having a distorted orthorhombic-simple structure with approximate lattice parameters of a/b/c = 5.4197/5.8520/7.6413 A and Y3Al5O12 having a tetragonal-simple crystal structure, have been identified in the steel. Two aluminum iron oxide phases and one aluminum titanium oxide phase, which are not known to have been identified previously in steels, have been found in the PM2000 steel. They have been determined to be aluminum iron oxide, Al2Fe2O6 having an orthorhombic crystal structure with the lattice parameters a/b/c = 7.235/5.926/ 7.502 A, and aluminum iron oxide, Al3FeO6 having a body-centered cubic crystal structure with an average lattice parameter of 3.047 A, as well as aluminum titanium oxide, Al 3Ti5O2 having a face-centered cubic crystal structure with an average lattice parameter of 6.923 A. The PM2000 steel contains a small amount of Al2Fe2O6, Al3FeO6, Al3Ti5O2 and Al2O3 phases with a large size and block/ or spherical morphology. © 2013 ISIJ.