Data are presented from tensile tests of commercial Nb-based alloy C103 (Nb-10Hf-1Ti, by wt pct) at temperatures of 1550–1750 °C and true-strain rates of \({3}\times 10^{-5}\) to \(3 \times 10^{-3}\,\hbox {s}^{-1}\) . Changes in strain rate generated pronounced short-term transients in flow stress. These transients are of the inverse type characteristic of solute drag creep (SDC). C103 produced large tensile elongations of 150–200 pct and strain hardened during plastic deformation. Test data provide an average strain-rate sensitivity of 0.29 and an activation energy for creep of 340 kJ/mol. Short-term transient data indicate a stress dependence for dislocation glide velocity of \({\bar{v}} \propto \sigma ^{2.7}\) and for mobile dislocation density of \(\rho \propto \sigma ^{0.7}\) . The deformed microstructure contains indistinct subgrains and steep strain gradients. All data indicate deformation by SDC controlled by the diffusion of Hf solute atoms for the range of conditions examined. Data from plastic flow transients suggest that creep rates for C103 available in the literature are likely from the primary creep region. When that is considered, data from the literature and the present study are in good agreement.
