Mechanisms of anelasticity in Fe–Ge-based alloys

Internal friction (IF) effects in a series of Fe–Ge–C alloys with 3–27 at.%Ge and about 0.01–0.04 at.%C have been examined and are related to possible mechanisms of anelasticity according to the different alloy structures. While Fe–3 at.%Ge and Fe–12 at.%Ge are bcc and show distinct Snoek-type relaxation, this relaxation is absent in Fe–27 at.%Ge with hexagonal structure. Here a pronounced Zener relaxation at elevated temperatures is observed. The mixed structures (bcc + hexagonal) of Fe–19–21 at.%Ge give rise to a non-thermally activated peak which already appears in Fe–12 at%Ge and may be due to ordering and/or vacancy complexes. In the temperature range below room temperature two neighbouring peaks are detected in the bcc structures which are supposed to be related to dislocations.