| In this paper, coating and PTA (plasma Transferred arc) surfacing process are used to synthesize in-situ Fe 3 Al inter-metallic compound coating on mild steel substrates (Q235). The microstructure and composition of the coating were investigated by optical microscopy, X-ray, scanning electron microcopy. It is found that the Fe 3 Al inter-metallic compound coating can be synthesize in-situ during the coating and PTA cladding process.The coating consists of phase Fe 3 Al,FeAl,α-Fe and Al2O3. The structural morphosis is the coarse columnar grain, which is composed of a lot of fine lath Fe 3 Al needle grains. The orientations of needle grains are different and distributed randomly. Following the increasing of the temperature of test plate, the Fe 3 Al whiskers in the coating become large and the quantities are increasingly. The white-bright band occurred between the coating and the substrate, which proved metallographic bond. The hardness of the coating rise increasingly from the substrate line to the surface of Fe 3 Al inter-metallic compound coating. The clad alloying coating has the maximum hardness value, reduce sequentially to the base body in the alloying area, and the hardness value of substrate is least. The coatings have increased the hardness of the base body greatly and well anti-friction.This method can be used both to manufacture new parts and to repair the invalid parts used under special conditions. It has very important social and economic benefits.
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