Internal friction mechanism of Fe–19Mn alloy at low and high strain amplitude

Fe–Mn damping alloy, which can decrease the vibrating and noise effectively, will be widely applied to household appliances, automobiles, industrial facilities, etc. In this paper, the internal friction mechanism of Fe–19Mn alloy at low strain amplitude (10−5 range) and high strain amplitude (10−4 range) was investigated. The internal friction was measured using multifunction internal friction equipment and reversal torsion pendulum. The microstructure was observed using scanning electron microscopy. The phase transformation temperatures were determined using differential scanning calorimetry. The results indicated that the internal friction of Fe–19Mn alloy after solution treating was related to strain amplitude. The internal friction mechanism was believed to the movements of four damping sources (ε-martensite variant boundaries, stacking fault boundaries in ε-martensite and γ-austenite, γ/ε interfaces), which could be explained using the interactive movements of Shockley partial dislocations and point defects. At low strain amplitude (10−5 range), the bowing out movements of Shockley partial dislocations are the main moving mode of generating internal friction. At high strain amplitude (10−4 range), however, the breaking away movements of Shockley partial dislocations are the high internal friction mechanism of Fe–19Mn alloy.