Formation of intragranular nanocavities in the Cr2O3 layer during the corrosion of Cr3C2+Cr coated ZirloTM

Intragranular nanocavities were observed in the Cr2O3 layer of a Cr3C2+Cr coated ZirloTM specimen corroded in steam at 1200 ℃ for 1h. By comparing the coated specimen that was quenched from 1200 ℃ with the one that was not, we considered the root cause of the intragranular nanocavities in Cr2O3 was that the nanocavities that formed in the original coating were trapped into the Cr2O3 grains during the corrosion process. This explanation may also apply to the formation of intragranular nanocavities in single metal Cr-coated zirconium alloys corroded at high temperatures.