Effect of Ti on the growth of the Fe–Al layer in a hot dipped Zn–6Al–3Mg coating

Abstract

This present study discusses the effect of Ti addition to a Zn–6Al–3Mg galvanizing bath on the growth of an Fe–Al alloy layer. When the Ti content in a Zn–6Al–3Mg bath is less than 0.052wt.%, a subsequent increase of Ti in the bath causes a reduction in the average thickness of the resulting FeAl3Znx layer and the Fe2Al5Znx layer. The restraining effect of Ti on the growth of the Fe2Al5Znx layer is attributed to the occupation of Ti atoms in vacancies within the Fe2Al5Znx phase. The average thickness of the FeAl3Znx and Fe2Al5Znx layers increases significantly when the Ti content exceeds 0.052wt.%. The linear growth of the FeAl3Znx layer suggests that an interfacial reaction controls the growth process. The growth curve of the Fe2Al5Znx layer is parabolic, implying that its growth is controlled by the diffusion of Fe atoms. The effect of Ti on the growth of the Fe–Al alloy layer in the Zn–6Al–3Mg bath with different amounts of Ti has been explained based on different mechanisms.