Growth kinetics of aluminum-bearing intermetallic layer on tool steel

The growth kinetics and morphology of intermetallic compounds at the interface of H13 tool steel and A380 molten aluminum alloy have been investigated through immersion experiments in the temperature range of 680 to 740 degrees C. The effect of nitride coating of the surface of H13 steel on the formation and growth of intermetallic layers has also been studied. The results of scanning electron microscopy indicated that three intermetallic layers are formed at the interface, Al8Fe2Si, Al5FeSi, and Al12Fe5Si. Nitride coating decreased the overall intermetallic layer thickness at temperatures between 680 and 740 degrees C. It decreased the number of layers at 680 degrees C; the Al12Fe5Si layer was not formed. Kinetics study of the interfacial reaction between H13 steel samples and A380 aluminum alloy revealed parabolic growth. The growth rate of the intermetallic layer was evaluated and the activation energy was found to be 40 and 158 kJ mol(-1) for H13 steel and nitride-coated H13 steel, respectively.