Korniyets A. Low-temperature acoustic and elastic properties of Hf and Zr pure metals and Zr-based amorphous alloys

New fundamental data of the acoustic, elastic, and thermophysical properties of Hf and Zr pure (99.7-99.98%) metals, and Zr-based amorphous alloys were obtained in temperature region from 78 to 300 K. For the first time for Hf and Zr pure metals the resonant effects of internal friction and for Hf the relaxation (Bordoni-type) effects are found at the megahertz frequency range (20-150 MHz) to be caused by dislocation friction. In the ultrafine-grained pure (99.98%) Zr in the non-equilibrium grain-boundary region, the processes of "dynamic return" under the conditions of micro-stress of thermal anisotropy were revealed for the first time. For the first time, in Zr-based amorphous alloys, new mechanisms for the dissipation of mechanical energy, caused by the "migration" of cluster-boundary atoms under alternating ultrasonic deformations, were discovered. The size of the medium ordering region of the Zr41.2Ti13.8Cu12.5Ni10Be22.5 and Zr52.5Ti5Cu17.9Ni14.6Al10 alloys, which was 0.98 and 1.05 nm, respectively, was determined within the framework of the model of effective bulk packaging of clusters. As a supplement (for comparison with amorphous alloys), data on the acoustic and elastic properties of the high-entropy crystalline alloy Al0.5CoCrCuFeNi were obtained.