Internal friction and shear modulus in aluminium-Zn alloys after neutron irradiation at 760K

A sample of Al-Zn alloy with 4 at% Zn was measured before and after neutron irradiation with a total neutron dose of 1.44 x 1017 n/cm2 at liquid nitrogen temperature. The sample was then annealed to room temperature while the internal friction and shear modulus was measured. The internal friction measurement before irradiation showed up two peaks, not very well distinguished at 238 and 256 K. After irradiation a peak is detected at 256 K, a main peak at 293 K with a subpeak at 275 K. A second annealing was carried out on the sample and this time a peak was observed at 256 and 275 K. The subpeak at 275 K is not clearly observed. The recovery of shear modulus is similar to that of the residual electrical resistivity after low temperature neutron irradiation. (author)