Effects of various rare earth oxides on morphology and size of oxide dispersion strengthening (ODS)-W and ODS-Mo alloy powders

Abstract

Ultrafine oxide dispersion strengthening (ODS)-Mo and ODS-W alloy powders containing different types of oxide nanoparticles were successfully synthesized by spraying method (solid−liquid mixing method) combined with the reductions with carbon black and hydrogen in sequence. It is concluded that the solution concentration and type of rare earth oxide have no effect on the grain size of ODS-Mo alloy powder, but have obvious effect on that of ODS-W alloy powder. The higher the concentration of rare earth solution is, the smaller the average grain size of ODS-W alloy powder is. Furthermore, compared with doping with CeO2, the grain sizes of reduction products of La2O3 and Y2O3 doped WO3 are relatively larger. Compared with the undoped case, there is almost no change for grain size of ODS-Mo alloy powder, while the grain size of ODS-W alloy powder becomes much larger. This is probably due to the appearance of the composite oxide (such as La2WO6) formed by the reaction between tungsten oxide and rare earth oxides, which promotes the heterogeneous nucleation and growth of tungsten grains during the reduction process of ODS-W, while there is no complex oxide composed of molybdenum and rare earth oxides in the reduction process of ODS-Mo.