The Effect of Nb on the Recrystallization and Grain Growth of Ultra-High-Purity α-Fe: A Combinatorial Approach

A combinatorial approach to the problem of the effect of Nb in solid solution on the conditions for recrystallization and grain growth in ultra-high-purity (UHP) α-Fe is presented. It is shown to be an efficient means for estimating parameters such as the binding energy of solute to grain boundaries, the transboundary solute diffusivity, and the intrinsic mobility of grain boundaries, crucial for practical applications of existing solute drag theories to questions related to alloy design. Using a Fe-Nb diffusion couple (Nb contents ranging from 0 to 0.095 wt pct) transformed within a temperature gradient (RT-850 °C), the boundary between the recrystallized and unrecrystallized regions and the grain growth behavior as a function of Nb content and temperature could be quantitatively rationalized using the slow branch of Cahn’s solution to the solute drag problem.