Vatazhuk O. Acoustic spectroscopy of low-temperature dislocation processes in nanostructured metals

The thesis is devoted to solving an important problem in the field of solid state physics, namely, obtaining information on dynamic elastic and inelastic properties of nanostructured Cu, Cu-Nb, Zr and Ti in a wide temperature range using acoustic spectroscopy, studying their stability by tracking at room temperature and high-temperature annealing, as well as the establishment of microscopic mechanisms of low-temperature acoustic resonances, which have a dislocation nature. It was found for the first time that the peaks of internal friction found in nanostructured copper and highly fragmented nanostructured fibrous composite Cu-32% vol. Nb are determined by the low-temperature dynamics of the movement of dislocation segments in the primary and secondary copper and copper matrix Peierls. It is also shown that the relaxation of internal friction near 250 K, detected earlier in the coarse-grained annealed Zr, remains after SPD, but its height increases by about 10 times, and the localization temperature shifts to low temperatures. In addition, after SPD, a new peak of internal friction was registered for the first time in the region of moderately low temperatures near 80 K. The insufficient stability of the structures of the UFG and CG of samples created by applying various SPD schemes was established. The temperature dependence of the Young's modulus of the ENS(T) nanostructured samples revealed a characteristic characteristic of low-temperature elastic moduli of glasses as a result of the interaction of acoustic oscillations with dislocation TLS, RS, and HO. It is hypothesized about the dislocation nature of the glass subsystem (or “phase”) in NS metals obtained by SPD.