Effect of cooling rate on damping capacity of Fe–Cr based ferromagnetic metal alloy

Abstract

The Fe–15Cr–3Mo–0.5Si alloy was treated by furnace cooling, air cooling or water cooling after annealing at 1100°C for 1h in vacuum atmosphere. The damping performance of the as-treated alloys was tested with dynamic mechanical thermal analyzer and the effects of different cooling rates on phase, microstructure, coercive force and damping capacity were investigated. The results show that the cooling rates have no influence on the crystalline phase and grain sizes of the Fe–15Cr–3Mo–0.5Si alloy. The phase of the as-treated alloys is a single α-Fe. Moreover, Cr- and Mo-containing carbide precipitation is detected on alloy grain boundary of the furnace-cooled alloy, while no precipitated phase on the alloy grain boundary of the air-cooled and water-cooled alloy. In addition, the furnace-cooled alloy shows the smallest coercive force comparing with the air-cooled alloy, and the water-cooled alloy shows the biggest coercive force. The peak values of logarithmic decrement δ of furnace-cooled, air-cooled and water-cooled alloy are 0.209, 0.188 and 0.175 respectively. The gradual decrease of the damping capacity with increasing cooling rate for the alloy mainly lies in the discrepancy of their micro internal stress.