Effects of Cr, Mo, Al, Zr, Y2O3 on the Microstructures and Tensile Properties of ODS Ferritic/Martensitic Alloys

To develop an advanced ODS alloy for core structural materials for next-generation nuclear reactor system applications, effects of alloying elements such as Cr, Mo, Al, Zr and Y2O3 on microstructures and tensile properties of ODS ferritic/martensitic alloys were investigated. The ODS alloys were fabricated by mechanical alloying, hot isostatic pressing, and hot rolling processes. The Cr concentration revealed little effect on the tensile strength, but it affected the grain morphology as a result of phase transformation. Mo acted to increase the tensile strength at an elevated temperature. Both grain and oxide particle sizes were significantly coarsened by Al addition. These enlargements led to a decrease in tensile strength but improved the elongation. Minor addition of Zr enhanced the tensile strength, and an increase of Y2O3 addition deteriorated the elongation. These results could be very useful in optimizing the alloying element concentration of ODS alloys with superior out-of-pile mechanical properties. †(Received July 18, 2013)