Stabilizing Supersaturation with Extreme Grain Refinement in Spinodal Aluminum Alloys.

Supersaturated solid solutions can be formed in alloys from various non-equilibrium processes, but stabilizing the metastable phases against decomposition is challenging, particularly the spinodal decomposition which occurs via chemical fluctuations without energy barriers to nucleation. Herein, we found that spinodal decomposition in supersaturated Al(Zn) solid solutions can be inhibited with straining-induced extreme grain refinement. For the refined supersaturated grains in the nano-scale, their spinodal decomposition is obviously resisted by the relaxed grain boundaries and reduced lattice defects. As grains are refined below 10 nm the decomposition is completely inhibited, in which atomic diffusion are blocked by the stable Schwarz crystal structure with vacancy-free grains. The extreme grain refinement offers a general approach to stabilize supersaturated phases with broadened compositional windows for property modulation of alloys. This article is protected by copyright. All rights reserved.