Abstract Analytical electron microscopy has been employed to reveal metastable structures in near eutectic niobium-germanium alloys which were processed in a 100 meter drop tube. Drop masses were generally 300 to 400-mg, with undercooling as much as 0.14-Tm prior to recalescence. Specimens which were slightly hypoeutectic and undercooled 0.10 below the liquidus prior to recalescence contain β cells which grew with solute rejection, and an intercellular metastable α + Nb5Ge3 eutectic. When deep undercooling was followed by Rapid Solidification Processing (RSP) via splatting onto a copper block, cellular β formed with solute entrapment, though the high cooling rate of RSP did not prevent the formation of Nb5Ge3 precipitates from the Ge enriched β. In one specimen, an amorphous Nb-Ge phase has been identified.
Metastable structures in drop tube processed niobium based alloys
Advances in Space Research ; 6 , 5 ; 123-126
1986-01-01
4 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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