Structures of metals are examined at the atomic level, as follows: (1) reaction rates of diffusing point defects with complexes of probe atoms and point defects are studied to determine local lattice strains in metals; (2) Lattice sites of probe atoms in nanoscale metal clusters with radii less than 100 nm are measured to characterize how the structures of clusters depend on their size; (3) High temperature ordered alloys are examined to find equilibrium point defects and diffusion mechanisms; (4) Phase transitions and defect structures are analyzed in shape memory alloys. Perturbed angular correlation measurements and Mossbauer spectroscopy are the primary experimental tools employed in the research.