Microstructural characterization and role of glassy layer developed on inconel 690 during a nuclear high-level waste vitrification process

The interaction of Inconel 690 metallic components with borosilicate melt leads to development of a partially amorphous and a partially crystalline layer within borosilicate melt adjacent to the interface. Such a heterogeneous layer is referred to here as a glassy layer. In the present investigation, the glassy layer is constituted of several phases, e.g. a Cr2O3 layer, a Ni2CrO4 needle, and NiCr2O4 cubic phases. Incorporation of such a glassy layer within the melt pool can lead to significant microstructural changes in the melt. Formation of barium chromate and nickel silicate has been observed in a sodium barium borosilicate melt with excess amount of Cr2O3 and NiO, respectively.