Thermal stability of nanocomposite metals: In situ observation of anomalous residual stress relaxation during annealing under synchrotron radiation Original Research Article

The thermal stability of nanocomposite metals (a nanostructured copper matrix embedding niobium nanotubes) is investigated via time-resolved in situ annealing under synchrotron high-energy X-rays. The diffraction peak profile analysis demonstrates that internal-stress relaxation begins in the Nb nanotubes at a temperature far below the bulk recrystallization temperature and follows size-specific regimes originating from a proximity effect with the nanostructured Cu matrix: the increased Cu–Nb interface surface disrupts internal-stress relaxation processes, confirming the larger thermal resistance of nanostructured materials.