Thermal spraying of transition metal aluminides: An overview

This paper summarises the scientific effort made during the last decades by the materials science community to understand, evaluate and improve the behaviour of aluminide intermetallic coatings obtained by means of thermal spray technologies, basically those based on transition metals such as iron, nickel and titanium. These materials have risen a great interest owing to their good specific properties and excellent resistance to hostile environments; they have been even reported to be good candidates someday for superalloys replacement. However, their poor room temperature ductility has limited their fabrication and commercialisation as bulk materials. Thanks to parallel improvements on processing methods and metallurgy research, some of these drawbacks are becoming ready to be outcome.One interesting alternative is then the fabrication of the component with a good load-carrying capability accomplishing the in-service mechanical requirements and covering it with a protective coating material able to withstand the atmosphere conditions. Thermal spray methods have been proved to be very effective for such purpose; this review exposes from the structure–properties coating relationship point of view, the existing investigations regarding the above mentioned aluminides.