The research on the microstructure and damping behavior of a new-type Mn-Ni damping alloy

Abstract A new-type Mn-Ni damping alloy named Mn 40 with the Mn content of 40wt% was developed. The XRD, Thermal expansion analysis, optical microscopy, SEM, EDS and the Vickers-hardness tests were used to analyze the effect of processing and heat treatment on microstructure of the alloy. The internal friction was measured by forced resonance viberation method to study the effect of solution treatment and ageing temperature and time on the damping behavior. And the damping mechanism of the alloy was analyzed. The results showed that in the temperature range of 450∼650 °C the body-centered tetragonal (bct) phase transformation occurred in the face-centered cubic (fcc) alloy matrix, and the body cubic centered second phase precipitated. The alloy has optimal damping behavior after solution treatment and ageing treatment at 550 °C. The complex phase structure precipitated in the temperature range of 450∼650 °C is considered to be the main reason for the increase of internal friction of the alloy.