Comparison of ultrasonic velocity changes caused by dissolution of hydrogen, deuterium, and tritium in bcc vanadium and niobium

Abstract

The effects of dilute additions of deuterium (D) and tritium (T) on the elastic moduli of single crystals of Nb and V were measured at room temperature. The coefficients ΔC44/C44 and ΔC′/C′, per at.% isotope, are evaluated and compared with published data for H additions and previous measurements of D additions. The agreement among data from different laboratories is well within experimental error. The ΔC′ effects in Nb are isotope dependent and closely related to the square root of the inverse mass. In the case of V, the ΔC′ effect is the same for T and H but smaller for D, suggesting a possible change from tetrahedral to octahedral site occupancy with increasing isotope mass.