Transition Metal Aluminide Coatings and Initial Steps on Additive Manufacturing

Abstract

During the last decades, Fe-, Ni-and Ti-based aluminides have been studied in terms of bulk materials with an effort to develop alloying and processing strategies to overcome their low ductilities and toughness compared to conventional alloys. Whenever significant improvements can be addressed in this direction, they will be opened to an extensive range of industrial applications, especially those related to high temperature resistance requirements. In parallel, progressing interest has also been focused on their application as protective layers. This chapter is intended to provide a review of the evolution that has been made mainly during the last two decades of the several coating technologies devoted for this purpose. From thick to thin coatings are revised, with insight into coating microstructures and properties as well. Lack of space has forced the selection of those technologies arising most interest within last years; therefore, the content will follow this order: joining (laser cladding and electrospark deposition), thermal spraying (high velocity oxygen fuel and cold spraying) and physical vapor deposition (magnetron sputtering and cathodic arc deposition).

Additive Manufacturing of β-NiAl by Means of Laser Metal Deposition of Pre-Alloyed and Elemental Powders

“…The intermetallic β-NiAl phase exhibits a low density of only two thirds of comparable Ni-based superalloys. Moreover, the high melting temperature of 1638 °C, superior thermal conductivity and an outstanding oxidation resistance at elevated temperatures make β-NiAl-based alloys promising materials for high-temperature applications in future turbine engines, which has been known since the 1960s ( Table 1 ) [ 2 , 3 , 4 , 5 , 6 , 7 ]. However, the unsolved issues of limited ductility and fracture toughness at room temperature, as well as a poor strength at high temperatures, have prevented its transfer to industry so far [ 2 , 3 ].…”