The drawback of overthicknesses of coatings when galvanizing silicon s
teels may be overcome by adding titanium to the zinc bath. In order to
understand reactivities between substrates and the alloyed zinc bath,
the ternary phase system Fe-Zn-Ti at 450 degrees C was investigated u
sing diffusion experiments. Three kinds of diffusion couples were used
(solid/solid, solid/liquid and solid/vapour under controlled pressure
) to describe the whole isothermal section at 450 degrees C. The solid
-liquid reaction accurately reveals the zinc rich corner of the diagra
m in connection with galvanizing. The analysis of the different phases
in each coating allows to determine Ti solubilities in the Fe-Zn inte
rmetallic compounds and to new equilibria in the Fe-Zn-Ti system at 45
0 degrees C. Moreover, we show that the diagram obtained, characterize
d by a huge Gamma(2) domain is metastable. The stable diagram, obtaine
d with long time experiments is characterized by a more restricted Gam
ma(2) solid solution which extends from the Gamma(2) - FeZn4 binary co
mpound to the Gamma(2) - TiFe2Zn22 ternary dress.