A transmission electron microscopic study was made of the deformation microstructures of Nb-20mol%Mo single crystals which contained 0.03 to 0.65mol%O, and of a Nb-40Mo-0.05mol%O single crystal, after compression to about 4% of plastic strain at 298, 973 or 1473K. At 298K, screw dislocations predominated in all of the alloys. At 973K, in Nb-20Mo-0.03O and Nb-40Mo-0.05O, the dislocation microstructure contained the same numbers of edge dislocations, and small edge dipoles that tended to aggregate into clusters. In Nb-20Mo-0.65O, however, the arrangement consisted of long glide loops lying parallel to the screw direction. At 1473K, edge dislocations predominated in all of the alloys. It was concluded that O atoms impeded screw dislocation motion at 298 and 973K, that the influence of O on screw segments was significant at 973K and that, at 1473K, O atoms impeded edge dislocation motion. It was deduced that an O-Mo atmosphere formed around dislocations.

Oxygen-Molybdenum Interaction with Dislocations in Nb-Mo Single Crystals at Elevated Temperatures. E.Miura, K.Yoshimi, S.Hanada: Acta Materialia, 2002, 50[11], 2905-16