Correlation between anelastic response and microstructure of 5N-Al thin foils

The anelastic behavior of 5N-Al thin foils with three different thicknesses (10, 50 and 125 pm) was investigated in the temperature range from 300 to 720 K through Mechanical Spectroscopy (MS) measurements performed by using a completely automated vibrating reed analyser. Two relaxation peaks P1 and P2 and a relevant high temperature background were observed in the thinnest samples whereas only the grain boundary peak (P-GB) was observed in the thickest ones. Detailed TEM observations and X-ray diffraction (XRD) measurements indicate that defective structures depend on foil thickness and suggest that the origin of P1 and P2 peaks is connected to the vibration dynamics of isolated dislocations not organized in networks. P1 has been attributed to the combination of dislocation motion through the stress field of other dislocations and thermally activated cross slip, while P2 is due to the movement of jogs assisted by pipe diffusion. In addition to anelastic effects due to dislocation vibration, permanent grain boundary sliding seems to contribute to the high temperature background observed in the thinnest foils. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The anelastic behavior of 5N-Al thin foils with three different thicknesses was studied using Mechanical Spectroscopy. Different relaxation peaks were observed in samples with different thicknesses, and the defective structures were found to depend on foil thickness. Additionally, permanent grain boundary sliding was found to contribute to the high temperature background in the thinnest foils.