Interfacial strained structure and orientation relationships of the nanosized oxide particles deduced from elasticity-driven morphology in oxide dispersion strengthened materials

Fe-Cr-Ti-Y2O3 oxide dispersion strengthened materials have a high density of nano-oxides (Y, Ti, O) that are stable at high temperature. In this work based on transmission electron microscopy it is shown that the interfacial strained structure and orientation relationship can be determined by using the elasticity-driven morphology of the nanosized particles after coarsening at 1573 K. In a Fe-14 Cr-1 W-0.3 Ti-0.3 Y2O3, most of the coarsened phases found are Y2Ti2O7 particles adopting a cubical shape. They are embedded with a cube-on-cube orientation relationship with the matrix, while a few Y2O3 particles are embedded in both cube-on-cube and cube-on-edge orientation relationships with the matrix. This morphological transformation could reveal the coherent misfitting character of the nanosized parent phases. The kinetics of the elasticity-driven morphology is different for both phases. Based on the supersphere approach, the elastic and interface energy calculation is proposed. The corresponding value of the (1 0 0) interface energy is 260 mJ m(-2) for Y2Ti2O7 particles and 350 mJ m(-2) for Y2O3 particles. The particle evolution during thermal annealing and (Y, Ti, O) coarsening resistance system is then discussed. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.