Characterization of Fe-Al intermetallic phases formed during hot-dip Al coating on carbon steel C45

Sophisticated metallographic techniques helped reveal numerous new features developed at the inner interfaces of the hot-dip aluminized C45 carbon steel specimens. Multi-intermetallic phases composing of Fe2Al5, Fe4Al13, FeAl3, and FeAl were identified whereby it was also found that the FeAl3 phase did not inherent from Fe2Al5, rather it is the Fe4Al13 phase that exists at the outermost layer of Fe2Al5 toward the aluminum topcoat where the Fe2Al5 layer has the most prominent grain size. In addition, the Gibbs free energies are consistent and underline the preferential growth of the Fe2Al5 phase having Delta G degrees = - 197.6 kJ/mol at 700 degrees C.

Automated summary

Sophisticated metallographic techniques were used to identify and study various new features developed at the inner interfaces of hot-dip aluminized C45 carbon steel specimens. The study revealed the presence of multiple intermetallic phases, with Fe2Al5 being the core phase and Fe4Al13 existing at the outermost layer of Fe2Al5. It was also found that the FeAl3 phase did not originate from Fe2Al5, but rather from Fe4Al13. The Gibbs free energies supported the preferential growth of the Fe2Al5 phase.