Unusual thermal stability of nano-structured ferritic alloys

A scientific question vitally important to the materials community is whether there exist "self-assembled" nanoclusters that are thermodynamically stable at elevated temperatures. Using in situ neutron scattering, we have characterized the structure and thermal stability of a nano-structured ferritic alloy. Nanometer sized nanoclusters were found to persist up to similar to 1400 degrees C, providing direct evidence of a thermodynamically stable alloying state for the nanoclusters. High-temperature neutron diffraction measurements show a stable ferritic matrix, with little evidence of recrystallization or grain growth at temperatures up to 1300 degrees C. This result suggests that thermally stable nanoclusters and the oxygen-vacancy interaction limit the diffusion of Fe atoms and hence the mobility of grain boundaries, stabilizing the microstructure of the ferritic matrix at high temperatures. (C) 2012 Published by Elsevier B.V.