The high temperature corrosion resistance of steel was improved with a Fe-Al
intermetallic coating applied to Steel-45 by light beam
alloying. The effect of alloying processing parameters (the preplaced powder mass, m , and the heat input, q ) on the chemical composition,
microstructure and
phases of the alloying
coatings was investigated by scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction. The results show that reducing the specific heat input E (E=q/m) reduces the width and penetration of the alloying molten pool, which reduces the Fe content and increases the Al content of the coatings. The experiments resulted in coatings with 2.4~19.2 Fe/Al
atomic ratios. The Fe/Al atomic ratio determined by the specific heat input is the most important factor affecting the microstructure and phases of the coatings. There are three kinds of
coating microstructures, α-Fe solid solution, α-Fe solid solution +Fe3Al intermetallic compound, and FeAl+AlFe3C0.5 intermetallic compounds. Reducing the heat input and increasing the preplaced powder mass both reduce the Fe/Al atomic ratio of the coatings, which favors the synthesis of the Fe-Al (Fe3Al and FeAl) intermetallic compounds.