Entwicklung Von Hochtemperaturlegierungen Auf Kobalt- Und Nickelbasis. UEber Niobium, Die Entwicklung Und Anwendung Von Nioblegierungen

Precipitation-hardening alloys on cobalt or nickel basis are still the best high-temperature structural materials for load-bearing components, taking into consideration the wide range of requirements that has to be met by the working properties. Modern developments are characterized by aseries of measures whose combined effects have rendered possible substantial im­ provements in the high-temperature properties of these alloys. In the case of the nickel alloys it has been possible to considerably increase the long­ time creep rupture strength and thus to raise the temperature limit for the load-bearing capacity, especially by increasing the aluminium and titanium contents in conjunction with very slight additions of boron and zirconium. Promising developments are to be noted for the cobalt alloys in respect of materials having high additions of tantalum or titanium and zirconium. In addition, in the case of cobalt-tungsten there is a development trend towards alloys containing less chromium or none at all with additions of rhenium, titanium and zirconium for special purposes in the fields of space travel. The development and technical control of the high-temperature alloys in particular with high contents of elements with an affinity for oxygen or nitrogen have been strongly promoted by vacuum metallurgy techniques.