Hot-dip aluminizing of Fe–Cr–B cast steel in Al–Ti–B alloy melt

The periodic layered structure (PLS) composed of alternative arrangement of Cr–Al–B MAB phase and FeAl3 was formed at the (Cr, Fe)2B/Al interface during hot-dip aluminizing (HDA) of Fe–Cr–B cast steel in molten Al. However, the effect of alloying element in the Al melt on the PLS was still unknown. This work focused on the effect of Ti on the interfacial reaction between Fe–Cr–B cast steel and molten Al–Ti–B alloy. The Ti atoms in Al–Ti–B alloy melt could partially replace the Cr atoms in the M-sites of the Cr–Al–B MAB phase contained in the PLS after it formed in-situ, leading to the formation of (Cr, Ti)–Al–B MAB phase solid solution. The B atoms in the melt absorbed by the Cr–Al–B MAB phase also accounted for the blackening of the Cr–Al–B MAB phase. It was the first time that the M-site MAB phase solid solution in the Cr–Al–B system was prepared by hot-dip aluminizing.