Editing Niobium (section)

===Superalloys===

Quantities of niobium are used in nickel-, [[cobalt]]-, and [[iron]]-based [[superalloy]]s in proportions as great as 6.5%<ref name="heister" /> for such applications as [[jet engine]] components, [[gas turbine]]s, rocket subassemblies, [[Turbocharger|turbo charger]] systems, heat resisting, and combustion equipment. Niobium precipitates a hardening γ<nowiki>''</nowiki>-phase within the grain structure of the superalloy.<ref name="Donachie">{{cite book|publisher = ASM International|date = 2002|isbn = 978-0-87170-749-9|title = Superalloys: A Technical Guide|url = https://archive.org/details/superalloystechn00dona|url-access = limited|first = Matthew J.|last = Donachie|pages = [https://archive.org/details/superalloystechn00dona/page/n36 29]–30}}</ref>

One example superalloy is [[inconel|Inconel 718]], consisting of roughly 50% [[nickel]], 18.6% [[chromium]], 18.5% [[iron]], 5% niobium, 3.1% [[molybdenum]], 0.9% [[titanium]], and 0.4% [[aluminium]].<ref name="super">{{cite web|url = http://www.msm.cam.ac.uk/phase-trans/2003/Superalloys/superalloys.html|title = Nickel Based Superalloys|first = H. k. d. h|last = Bhadeshia|publisher = University of Cambridge|access-date = 4 September 2008|url-status = dead|archive-url = https://web.archive.org/web/20060825053006/http://www.msm.cam.ac.uk/phase-trans/2003/Superalloys/superalloys.html|archive-date = 25 August 2006|df = dmy-all}}</ref><ref>{{cite journal|journal = Thermochimica Acta|volume = 382|date = 2002|pages= 55–267|doi = 10.1016/S0040-6031(01)00751-1|title = Thermophysikalische Eigenschaften von festem und flüssigem Inconel 718|language=de|author=Pottlacher, G.|author2=Hosaeus, H.|author3=Wilthan, B.|author4=Kaschnitz, E.|author5=Seifter, A.|issue = 1––2| bibcode=2002TcAc..382..255P }}</ref> 

These superalloys were used, for example, in advanced air frame systems for the [[Gemini program]]. Another niobium alloy{{clarify|date=November 2023}} was used for the nozzle of the [[Apollo service module|Apollo Service Module]]. Because niobium is oxidized at temperatures above 400&nbsp;°C, a protective coating is necessary for these applications to prevent the alloy from becoming [[Brittleness|brittle]].<ref name="hightemp" />