High temperature oxidation of beryllium modified intermetallic compounds of the niobium-chromium system

Intermetallic compounds based on the Laves phases NbCr2 and TiCr2 are of interest for high temperature applications. At temperatures where the high temperature strength and creep resistance of these compounds are excellent, their oxidation resistance is relatively poor. Beryllide compounds in the 3-Be, Ti-Be and Nb-Be systems (CrBe2, TiBel2, TiBez, NbBel2) on the other hand, exhibit excellent oxidation resistance even at temperaturets in excess of 1200' C, due to the formation of protective Be0 scales. The pure beryllides have relatively poor mechanical properties however. Therefore we have attempted to improve the oxidation resishnce of the Nb-Cr-Ti based Laves phases using alloying additions of beryllium. Alloys investigated include CrBe2, NbBe2 and NbCr2 with 10,25, and 33 atomic percent beryllium substituted for Cr. We have determined that there is a significant solubility of Be in NbCr2, Beryllium modified NbCr2 exhibits protective oxidation, with the growth of scales containing principally Cr2O3, and BeO