Low-temperature acoustic properties of nanostructured zirconium obtained by intensive plastic deformation

• Published in: Low temperature physics (Woodbury, N.Y.) N.Y.), 2011-02, Vol.37 (2), p.169-176
• Main Authors: Vatazhuk, E. N., Pal-Val, P. P., Natsik, V. D., Pal-Val, L. N., Tikhonovsky, M. A., Velikodny, A. N., Khaimovich, P. A.
• Format: Article
• Language: English
• ISSN: 1063-777X; 1090-6517
• DOI: 10.1063/1.3556667

The temperature dependences of the logarithmic decrement and dynamic Young’s modulus of polycrystalline coarse-grained and nanostructured Zr are studied at temperatures of 2.5 – 340 K . A nanostructured state of samples with grain sizes on the order of 100 nm was produced by intensive plastic deformation (IPD). The measurements were made using a two-component vibrator technique at frequencies of 73 – 350 kHz . A relaxation peak in the internal friction near 250 K was discovered in the coarse-grained, annealed Zr which is retained after IPD, but its height increases by roughly a factor of 10 and the localization temperature shifts to lower values. In addition, after IPD a new internal friction peak shows up at moderately low temperatures near 80 K . The activation parameters for the observed peaks are estimated and it is shown that they arise from different thermally activated dislocation processes: interactions of dislocations with impurities and kink pair formation in dislocations. It was found that IPD is accompanied by a significant (1–8%) reduction in the Young’s modulus because of quasistatic and dynamic dislocation effects. A glass-like anomaly appears in the temperature dependence of the Young’s modulus of nanostructured Zr at T < 20 K which may be determined by tunnelling and thermally activated relaxation of quasilocal excitations.