Oxidation mechanism of refractory Molybdenum exposed to oxygen-saturated lead-bismuth eutectic at 600 °C

The oxidation mechanism of refractory Molybdenum exposed to oxygen-saturated lead-bismuth eutectic (LBE) at 600 °C was investigated. The results show a hierarchical structure of multiple corrosion layers. Specifically, a nanostructured tetragonal MoO₂ is the first scale that forms on the Mo substrate, followed by development of an ultrafine-grained tetragonal lead molybdate (PbMoO₄) layer. On the top of this ultrafine-grained layer, there is a thicker scale that consists of micron-sized columnar PbMoO₄ and its upper part can be further oxidized into blocky monoclinic-structured Pb₂MoO₅. The formation of these multilayered scales is likely predominated by inward diffusion of oxygen and Pb.