The Growth of Intermetallic Phases on Iron Galvanized in an Aluminum-Bearing Zinc Bath at 450°C

Abstract

<p>This thesis is concerned with determination of the nature and growth characteristics of the intermediate phases formed on iron galvanized in Al-bearing Zn at 450°C, Long time equilibrium experiments have been carried out to explain the nature of intermetallic phases and their equilibria in the system Fe-Zn-AI at 450°C using electron probe microanalysis and metallographic techniques.</p> <p>The growth characteristics of intermediate phases formed on iron galvanized in AL-bearing Zn at 450°C have been investigated by metallography and low angle X-ray diffraction. It has been confirmed that the inhibition layer is composed of Zn-bearing Fe2Al5 and FeAl5. While the FeAl2 phase was erratically detected, we did not detect the presence of FeAl. X-ray diffraction data for FeAl2, so far missing from the ASTM X-Ray Data File, have been recorded. A correlation of our results and that of other workers with our newly investigated and proposed ternary isotherm at 450°C using an analysis via diffusion paths on the isotherm has produced a convincing rationalization of the inhibiting effect and the catastrophic interface instabilities which develop preferentially in stagnant baths after long times and with the higher bath Fe contents.</p>