Reaction Between Hot-Dip Aluminized Coating on Fe–Cr–B Cast Steel and Molten ZnCl₂ Salt

The reaction between MoAlB MAB phase and molten ZnCl₂ salt resulted in the formation of metastable Mo₂AlB₂ MAB phase. In our previous work, it was first discovered by us that the periodic layered structure (PLS) was formed at the solid (Cr, Fe)₂B/molten Al interface during hot-dip aluminizing and subsequent thermal diffusion treatment of Fe–Cr–B cast steel. The interaction between PLS form in situ, especially the Cr–Al–B MAB phase contained in the PLS, and molten ZnCl₂ salt was studied for the first time in this work. There were complex reactions between the PLS and molten ZnCl₂. Specially, the Zn²⁺ in the molten ZnCl₂ salt could partially occupy the positions of Al atoms in the Cr–Al–B MAB phase contained in the PLS through the A-site replacement reaction. The topochemical reaction was: Cr₃AlB₄(s) + ZnCl₂(l) → Cr₃(Al, Zn)B₄(s) + Zn(l) + AlCl₃(g).