Magnetic domain structure and damping capacity of Fe-13Cr-2.5Mo alloy

The magnetic domain structure and damping capacity of Fe-13Cr-2.5Mo (wt. %) alloy have been investigated in this paper. Dynamic mechanical analyzer (DMA) was used to test the damping behavior. Bitter technique was used to observe the magnetic domain structures. The results show that the furnace cooled alloy exhibits significantly higher damping capacity than air cooled alloy. The cooling rate has great effects on morphology of magnetic domain structure. For furnace cooled alloy there are many ‘tree pattern’ domain structures, which contain relatively large volume fraction of 90° magnetic domain walls and favor the damping behavior. However, no ‘tree pattern’ structure exists in air cooled alloy and there are mainly closure and spike domains. The 90° domain walls in spike domain are almost nonexistent and the volume fraction of 90° domain walls in closure domain is small. In addition, the mobility of these both domain structures is relatively poor. Therefore, this alloy exhibits a worse damping behavior.