Effect of dendritic segregation on the damping property of MnCu alloy

Through the sand mould casting mechod to control the solidification process, MnCu alloy can gain significant composition segregation of dendritic structure, which can further promote spinodal decomposition in the process of aging. Therefore, the sand mould casting method was an effective way to improve the damping property of MnCu alloy. In the present work, the effect of composition segregation of dendritic structure on the damping property was investigated systemly by torsion pendulum, OLYMPUS microscope, scanning electron microscope (SEM), dynamic mechanical analysis (DMA) and X-ray diffraction (XRD). Results show that, casting M2052 alloys in as-cast condition has a small amount of twin martensite and damping performance. When aged at 435℃ for 4 h, the damping performance of the casting M2052 alloy was improved obviously (δ=0.26), even more than forging M2052 alloy performance (δ=0.2). In the procces of aged treatment, the Mn-rich area of the dendritic structure further promotes the formation of high rich Mn area in nanoscale, and the M_s point was improved remarkablely (M_s=85℃). The more twin martensite was generated during the cooling process, so that the casting M2052 alloy have excellent damping performance.