Research On Damping Capacity And Corrosion Resistance Of Mn-Cu-Al-Sn Alloys

Due to the high speed operation of the mechanical system,more prominent vibration and noise problems are generated.Among them,Mn-Cu alloy is a damping material that can effectively achieve vibration and noise reduction.Although this type of alloy has a wide range of applications in the field of vibration and noise reduction,the imbalance of comprehensive performance（such as damping performance,mechanical properties,corrosion resistance）limits its further application.Therefore,there is an urgent need to develop a Mn-Cu based damping alloy having a good overall performance.Aiming at the deficiencies in the damping properties,mechanical properties and corrosion resistance of Mn-Cu based damping alloys,quaternary Mn was prepared by adding Al and Sn elements to the alloys by vacuum induction melting technique.Mn-（43-x）Cu-1.5Al-xSn（x=0,1,2,3）alloy.By means of damping property test,hardness test,tensile test,immersion corrosion test and OM,XRD,SEM and EDS characterization.The effects of different cooling methods after solution treatment on the damping properties of the alloy during aging,the effect of Sn content on the martensite transformation point and transformation amount of the as-cast alloy,and the corrosion behavior of the alloy were studied.Among them,Mn-42Cu-1.5Al-1Sn alloy was treated by solution at 850℃×2 h,then cooled by water,oil and air,respectively.And then aged for 1,2,4,6 and 8 h at 410℃.The results show that with the decrease of cooling rate,the time required for the alloy to reach the peak value of internal friction prolongs,while the peak value of internal friction increases gradually.The main reason is that the supersaturated vacancy concentration in the alloy is higher due to the rapid cooling after solution treatment,which leads to the excess vacancy concentration decomposition during aging process,but is not conducive to the improvement of the modulation degree.In as-cast alloys,the alloys with Sn content of 1 wt.%have better damping properties and mechanical properties.This is due to the higher martensite transformation point（68.6℃）and martensite transformation amount（15.3 vol.%）of the alloys,the increase of martensite transformation amount and the increase of lattice distortion,and the increase of twin density.At the same time,when Sn content is 1 wt.%,the solid solution strengthening effect of Sn element and the strengthening effect of twin grain boundary lead to the improvement of mechanical properties（tensile strength 495.4 MPa,elongation 48.3%）.For the corrosion resistance of the alloy,the alloy can be heat treated by different processes,and a stable and compact oxide film can be formed on the surface of the alloy under the heat treatment conditions of 600℃×0.5 h.Among them,when Sn content is 1 wt.%,the oxide film on the surface is the most compact and complete.Compared with the alloy without Sn element,SnO₂ in the oxide film can further improve its corrosion resistance.