Surface modification of 4340 steel with iron aluminides using high-energy-density processes

Iron aluminides possess several attractive properties including excellent resistance to oxidation and sulfidation in aggressive environments, and hence appropriate compositions of iron aluminides could find applications as high-temperature coatings. Iron aluminides can also be reinforced with hard, wear-resistant TiB ₂ particles thus achieving a combination of superior oxidation/sulfidation properties and excellent wear-resistance. In this paper, results of recent work involving the use of a high-powered laser and a high-density infrared plasma arc lamp to coat a representative steel, 4340, with iron aluminides, will be presented. It was observed that iron aluminide could be retained on the surface when either processing technique was used but its retention was a strong function of the processing parameters. In this paper, particular emphasis will be placed on the relationship between the structure and composition of the coatings, their properties, and processing parameters.