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.
 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.