Effect Of Heat Treatment On The Damping Capacity Of Mn-Cu Alloy And Research Of Laminated Damping Structure

In this paper the Mn-48.1Cu-1.55Al (wt.%) alloy was prepared by medium frequency vacuum induction melting technique. The damping composite laminated structure has been prepared by cast-in technique of Mn-Cu and Fe-Cr-Mo damping alloys. The cooling rate of solid solution and ageing time influence damping capacity of as-cast state Mn-Cu was investigated by X-Ray Diffraction (XRD), optical microscope, Scanning Electron Microscope (SEM) and the torsion pendulum. The effect of ambient temperature on damping capacity of Mn-Cu alloy was also studied. The interface bonding of laminated structure was analyzed by the interfacial shear strength, tensile strength. The damping capacity of laminated structure was researched under the condition of magnetic field, nonmagnetic field and different ambient temperatureAfter the solid solution at 850℃ for 0.5h, the Mn-Cu alloys were cooled with different cooling rate and were aged at different temperature. The result shows that the slow cooling rate is beneficial for the damping capacity of Mn-Cu alloy. The damping capacity of quenched Mn-Cu alloy has been the sharpest increased with solid solution and ageing. It is about 19.53 times as much as the quenched alloy. The Vickers hardness and damping capacity of the aged Mn-Cu alloy at different ageing temperature were investigated. It indicates that the best spinodal decomposition temperature within miscibility gap is 430℃.The quenched Mn-Cu alloy was aged at 430℃ for different time. The result shows that the damping capacity of the sample increases with increasing ageing time and then declines. The optimal damping capacity of the sample is achieved at 4hours ageing (Q-1=0.146), due to the Mn-rich areas formed during ageing treatment promote the martensitic transformation temperature. The damping capacity of the sample decreases at over-aged owning to the precipitate ofα-Mn. The optimal damping capacity heat treatment process of the Mn-Cu alloy is solid solution at 850℃ for 0.5hours and then immediately aged at 430℃ for 4hours. In addition, the effect of ambient temperature on damping capacity of Mn-Cu alloys was studied. The result shows that the damping capacity decreases with the increase of ambient temperature, that because of the reverse martensitic transformation caused by the increasing ambient temperature which made the decrease of twin martensite amounts.The laminated structure has achieved a good interfacial bonding. The interface of the laminated structure at the bottom of the ingot has formed a good metallurgical bonding, including well interfacial share strength (157.5MPa) and high tensile strength (156.98MPa). The interface of the laminated structure close to mold edge and the top of mold is composed of metallurgical bonding and mechanical bonding. The laminated structure includes two kinds of damping mechanism (ferromagnetic damping mechanism and twin damping mechanism). The ferromagnetic damping and twin damping will be inhibited by magnetic field and higher ambient temperature respectively. The laminated structure still has the damping capacity at the magnetic field and a high ambient temperature. But the ferromagnetic damping plays a limited role in laminated structure due to the stacking sequence, the scale and proportion of two alloys.