Effect of high strain amplitude and pre-deformation on damping property of Fe-Mn alloy

In order to investigate the effect of high strain amplitude (maximum 1.6 × 10−3) and large pre-deformation (maximum 15%) on the damping properties of Fe-Mn alloys, the damping properties of the alloys were measured by a computer controlled automatic inverted torsion pendulum, microstructures were observed by SEM and EBSD, and phases were identified by XRD. The results show that the damping performance decreases at first and then increases when the pre-deformation amount is higher than 10%, and the valley value is reached at about 12%. When the pre-deformation amount is more than 12%, the content of ε phase decreases, while the amount of γ austenite and α′ martensite increases, the ε martensite phase of the alloy is divided and appears finer, ε martensitic phase and γ austenite have better parallelism, the phase interfaces of γ/ε significantly increase, and more damping sources with better slippage are provided, resulting in gradually increasing of damping properties of Fe-Mn binary alloy. When the strain amplitude is greater than 1 × 10−3, the damping properties and strain amplitudes of the pre-deformation alloys do not always maintain an approximately linear relationship, which closely related to different characteristics of damping sources due to stress-induced phase transition and formation of different alloy microstructures.