Reduction in Defect Content of ODS Alloys

Oxide dispersion strengthened (ODS) alloys prepared by mechanical alloying (MA) and subsequent consolidation are of increasing interest for potential application in components for use in power generation and furnace applications. After MA, canned alloy powders are usually subjected to a series of heat treatments. These heat treatments, particularly those at higher temperatures, last long enough, many hours in some cases, for significant changes to occur within the powder charge or consolidated material. Such changes may be beneficial, such as the degassing of the powder in the can or the secondary recrystallisation of the consolidated alloy. However, this is not always the case and this work involves investigation of the microstructural evolution and tendency for oxidation of the alloys ODS-Fe3Al and PM2000 during heat treatment. Where the effects of high temperature annealing are found to be deleterious to alloy properties, routes are suggested whereby detrimental effects may be kept to a minimum; how oxidation may be inhibited, how alloy powder properties affect oxidation behaviour and how incidental microstructural changes may be controlled during annealing processes.