Mechanisms of anelasticity in Fe–13Ga alloy

Thermally activated frequency and temperature dependent anelastic effects in Fe–Ga alloys are practically not studied as yet in spite of the capacity of these alloys to dissipate energy of mechanical vibrations due to magneto-mechanical damping. In this paper we have studied iron-based composition with 13 at.% Ga. Several thermally activated peaks have been discovered and their activation parameters are evaluated by means of temperature and frequency dependent internal friction tests using free-decay and forced vibrations. Physical mechanisms are proposed for most of these peaks. In addition to thermally activated relaxation peaks, an irreversible internal friction peak is recorded due to structural transformation around 200 °C. This peak is frequency independent and is accompanied by inverted modulus behaviour. High damping capacity of Fe–13Ga alloy is confirmed.

Research highlights
► The Fe–Ga alloys, often named ‘Galfenol’, are known by their high damping capacity.
► Two Fe–Ga alloys of nominal compositions of the 3 and 13 at.% Ga are studied.
► The carbon Snoek-type peaks (Fe–C–Fe and Fe–C–Ga) are identified. The Zener relaxation, two subzero peaks and the grain boundary relaxation are recognized.