Published online by Cambridge University Press: 15 March 2011
In our past work, two types of nanometer-sized oxide particle were found in the commercial ODS (Oxide Dispersion Strengthened) ferritic alloy MA957. They were nonstoichiometric Y-, Ti-, O-enriched clusters (2 ∼ 15 nm) and stoichiometric Y2Ti2O7 (15 ∼ 35 nm). The particles which have an important role for the strengthening were confirmed to be nonstoichiometric Y-, Ti-, O-enriched clusters (denoted by YxTiyOz in this work). Based on that result, the stability and evolution mechanism of oxide particle at high temperatures were studied in this work. After annealing (1473 K × 1 h), most of the non-stoichiometric YxTiyOz particles were stable and their size increased very little. However, some these particles apparently became Y2Ti2O7 particles with increasing size and yttrium content. They possibly contributed to the growth of Y2Ti2O7.