Holding temperature dependent variation of damping capacity in a MnCuNiFe damping alloy

A Ni-added MnCuNiFe damping alloy is observed to show a smaller damping capacity degradation than other MnCu alloys during holding at room temperature. A step-increase mode of damping capacity appears in the MnCuNiFe alloy during holding at a higher temperature above Tt = 350 K, the phase transformation temperature of the alloy. The critical holding time corresponding to the onset of the step-increase mode of damping capacity has been related to the diffusion of carbon to the Mn sulfide precipitates in the alloy. Thermal cycling of the alloy to a lower temperature above the Tt may cause the formation of dislocations, which will decrease the damping capacity of the alloy, especially at high strain amplitudes above 1 × 10−5.