Elastic constants of niobium-molybdenum alloys in the temperature range −190 to +100°C

The adiabatic elastic constants were determined for niobium and niobium-molybdenum alloys of the following nominal compositions: 15, 25, 35, 50, 75, and 90 wt.% Mo. The c11, c12, and c44 elastic constants of these bcc alloys were tabulated between −190 and +100°C. The effects of compositional changes on the elastic constants were far greater than those due to temperature. An anomalous temperature dependence for c44 was found for the niobium-rich alloys. An analysis of the elastic constants in terms of central forces revealed that nearest-and second-nearest-neighbor force constants rise with molybdenum additions, with the latter tending towards a maximum as the composition of pure molybdenum is approached. This is thought to be associated with the filling of a d subband. The Debye temperatures were computed and found to be generally in good agreement with the calorimetrically determined values reported in the literature.