Effect of annealing treatment on damping capacity of Fe–7Al–0.5Ti alloy

The damping capacity of the Fe–7Al–0.5Ti alloy in different annealing conditions was measured using reversal torsion technique. A water-based magneto-fluid was used to analyze magnetic domain morphology of the alloy using optical microscopy. The experimental results show that there is a damping peak after annealed at 1000 °C × 1 h. The damping variation of this alloy depends on the domain wall mobility and its size that cause a critical temperature. Below the critical annealing temperature, the decrease of local internal stress and structure defects causes magnetic domains more easily to move. As a result, the damping capacity increases quickly. However, when this alloy is annealed over the critical temperature, the size of magnetic domains becomes so large that the domain wall area in metal decreases, making the damping capacity decreases as well.