Materials for elevated-temperature applications

Abstract Recent studies have been conducted in an effort to expand the current capabilities of superalloys and to explore materials which may extend application temperatures well beyond the celestial limits of the high temperature materials currently in use. Work on very high melting (melting temperature T m > 1650 °C) intermetallics has, to some extent, validated the potential of these materials. Specifically, Cr 2 Nb has been shown to possess both a very high strength at temperatures to 1300 °C and an excellent creep resistance. Efforts directed at intermetallic-intermetallic composite systems such as beryllide-reinforced Fe-40 wt.%Al have shown that the problem of interdiffusional degradation can be significantly inhibited through the formation of a “diffusional lock”. Finally, it has been found that electron beam cold-hearth can significantly enhance performance. Indeed, it has been found that electron beam cold-hearth refining of Inconel 718 resulted in a virtual elimination of inclusions anda sixfold increase in low cycle fatigue life.