Internal friction in single-crystal Al alloys after electron irradiation at low temperature

Internal friction in single crystal Al-Si, Al-Zn, Al-Ge, Al-Sn, and Al-Pb alloys are measured after electron irradiation at 78 K. The internal friction spectra in these alloys are very similar. Since the atomic size of Sn and Ge atoms is oversized as compared to the host atom, the internal friction peaks in these alloys are considered to be due to rearrangement of the type b first-neighbour configuration. The two peaks at 10 to 12 K and at 55 to 60 K are attributed to the 'frozen-free split' phenomenon. The former has tetragonal symmetry and the latter the trigonal symmetry. (author)