Internal friction and Young's modulus of Nb\u2083Sn between 6 and 300 K

Young's modulus and internal friction were measured in polycrystalline NB\u2083Sn between 6 and 300K. Below the martensitic transformation temperature a large rise in internal friction is observed, in agreement with recent observations. In this temperature range, the internal friction is found to be nearly independent of frequency, a behavior consistent with stress-induced wall motion between domains of the tetragonal phase as the main source of relaxation. Internal friction peaks observed at 140 and 260K in Nb/Nb\u2083Sn composite tapes are tentatively attributed respectively to an \u3b1 peak in Nb and hydrogen in the Nb\u2083Sn layer. Annealing at 750 \ub0C for 1/2h is found to decrease the transformation temperature from 49 to 40K, and to modify the softening of Young's modulus in this temperature range. Young's modulus at 6K is 46% of room temperature value and is unchanged by the annealing treatment.Peer reviewed: YesNRC publication: Ye