Atomic insights into the preferential dissolution of Laves phase of 9% Cr heat resistant steels in the strong alkaline solution

Two types of 9% Cr heat resistant steels were used to investigate the preferential dissolution mechanism of Laves phase in 8 mol/L NaOH solutions in an atomic scale by quasi-in-situ TEM analyses and first principles calculations. The dissolution of Laves phase is due to the unprotective oxide film. The dissolution rate of Laves phase was associated with the crystal orientation, and the stacking faults hinder the dissolution of Laves phase in a strong alkaline solution. Further, DFT calculations were used to illustrate the dissolution process of Laves phase, and the result is consistent with the TEM observation.