To investigate the effect of purity on damping capacity of FeMn alloy, the damping capacities of two alloys with different impurity content were measured using reversal torsion pendulum. The stacking fault probability and volume fraction of ε-martensite were determined using XRD and the microstructure was observed using OLYMPUS microscope. The results indicated that the damping capacity of the two alloys increased linearly with increasing strain amplitude. Impurity element content had great influence on the damping capacity of FeMn alloy. Compared with alloy 1(the impurity element content was 0.235%), the damping capacity of alloy 2(the impurity element content was 0.722%) decreased by nearly 20% when the strain amplitude was 4.5×10-4. It was because that the weak pinning points on Shockley partial dislocations increased with increasing impurity content, and the movement of Shockley partial dislocations became more difficult.
