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The oxidation behaviour of a carbon steel was investigated after modifying the surface in three different ways, namely: (a) physical vapour deposition of aluminium by a resistance heating evaporation technique; (b) diffusion annealing of predeposited aluminium; and (c) laser surface alloying with predeposited aluminium. While diffusion annealing at a temperature of 1023 K was found to result in the formation of Al 13 Fe 4 and Al 5 Fe 2 phases, laser surface alloying resulted in a case containing Al 13 Fe 4 and Al 2 Fe phases. The oxidation behaviour of all the above specimens was studied at 873 K for a total duration of up to 200 h. The mass change and morphological modifications to the surface were monitored at regular intervals of 25 h. It was observed that aluminising results in a substantial enhancement of the high temperature oxidation resistance in comparison with the untreated base material, by virtue of the superior oxidation resistance of the intermetallic phases formed on the surface. Furthermore, laser surface alloying was found to result in better oxidation resistance, in comparison with diffusion annealed and as deposited specimens.MST/4660

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