Abstract: An iron-nickel superalloy of the type IN 706 has an addition of 0.02 to 0.3 percent by weight of boron and/or 0.05 to 1.5 percent by weight of hafnium. By means of this addition, a virtual doubling of the ductility is achieved as compared with an addition-free iron-nickel superalloy of the type IN 706, while the hot strength is reduced only slightly. The alloy is particularly suitable as a material for rotors of large gas turbines. It has a sufficiently high hot strength. When locally acting temperature gradients arise unwanted stresses can occur to only a slight extent because of the high ductility of the alloy.

Abstract: An alloy based on a silicide containing at least chromium and molybdenum contains the following constituents in atomic percent: chromium 41-55, molybdenum 13-35 and silicon 25-35, or chromium 35-55, molybdenum 13-35, silicon 13-35, yttrium 0.001-0.3, and/or tungsten 0.001-10. This alloy is distinguished by a high oxidation resistance and still has a mechanical strength at temperatures of over 1000.degree. C. which favors its use as structural material in gas turbines.

Abstract: The alloy is based on doped iron aluminide Fe.sub.3 Al. It contains the following alloying constituents in atomic percent:______________________________________ 24 28 aluminum, 0.1 2 niobium, tantalum and/or tungsten, 0.1 10 chromium, 0.1 2 silicon, 0.1 5 boron, 0.01 2 titanium, ______________________________________the remainder being iron. The alloy is notable for a high oxidation resistance and corrosion resistance even at temperatures above 700.degree. C. and is preferably used in components which are exposed to oxidizing and corrosive actions at high temperatures and low mechanical stress.

Abstract: The iron-aluminum alloy comprises the following constituents in atom percent:______________________________________ 12-18 aluminum 0.1-10 chromium 0.1-2 niobium 0.1-2 silicon 0.1-5 boron 0.01-2 titanium 100-500 ppm carbon 50-200 ppm zirconium remainder iron. ______________________________________This alloy is distinguished by high thermal-shock resistance and, at temperatures of 800.degree. C., still has comparatively good mechanical properties. The alloy can be used advantageously in components such as, for example, casings of gas turbines, which, with comparatively low mechanical loading, are subject to frequent thermal cycling.