Laminates based on an iron aluminide intermetallic alloy and a CrMo steel

Laminates of an iron aluminide intermetallic alloy and a CrMo steel prepared by solid state bonding has been investigated to improve the oxidation resistance of the steel. Microstructural observation reveals that the joint is free of any defects, and columnar grains are evolved towards the steel from the joint interface at high temperatures above A3. A continuous change of composition is observed between the constituents, without the formation of an intermetallic phase. The formation of the columnar microstructure is explained by α nucleation at the joint interface caused by Al diffusion to stabilize α, followed by grain growth in the steel. The composite demonstrates high bonding strength due to sufficient interdiffusion between the constituents, and an improvement of the oxidation resistance of the steel due to Al diffusion from the intermetallic to the steel resulting in α-alumina oxide on the surface. The composite prepared by clad-rolling is found to be free of crack and warp, and exhibits outstanding resistance to oxidation. These results suggest that the composite based on iron aluminide intermetallic has a potential for oxidation resistant application.