INTERNAL-FRICTION AND SUBSTITUTIONAL-INTERSTITIAL INTERACTION IN NIOBIUM-BASED ALLOYS

The logarithmic decrement delta was measured in Nb-Mo(V)-O alloys with Mo(V) content up to 50 at.% using a low frequency (f=3-7 Hz) inverse torsion pendulum in the temperature range from 20 to 700 degrees C. The complex delta vs. T curves were analysed in terms of their constituent peaks using a computer. The parameters of these peaks were used to derive information on the distribution of oxygen atoms over octahedral interstitial sites differing in the number of Mo(V) atoms contained in the surrounding nearest-neighbour lattice sites. This information was used for determining the Mo(V)-O binding energy and the structure potential barrier for oxygen atom diffusion in alloys with strong (V-O) and weak (Mo-O) interactions.