The nature of the intermetallic layer which forms on the steel surface during immersion
in typical galvanizing baths for galvannealed (GA) sheets production has been investigated
on two commercial Titanium-stabilized Interstitial-Free (Ti-IF) steel substrates
galvanized in baths with different Al contents. Results from this study show that in both
cases the inhibition layer is biphasic and composed of a very thin Al-rich phase layer,
identified as Fe2Al5Znx, and a thicker Zn-rich phase layer
on top of it, identified as δ. Experimental results also show that the
Fe2Al5Znx phase layer becomes discontinuous
when decreasing the bath Al content. Discussions about the mechanisms of formation and the
final microstructure of this inhibiting layer are also tackled in this paper by means of
the Al-Fe-Zn ternary phase diagram at 460 °C and assumptions to justify any deviation from
thermodynamic equilibrium are as well proposed.