Effects Of Heat Treatment And Deformation On Microstructure And Damping Capacity Of Mn-Cu Alloys

For major problems of manganese copper alloys, this study proposed research content and technical routes. The phase structures, microstructure and damping capacity of rolled CuMn50 alloy were tested using x-ray diffractometer, scanning electron microscopy, electronic back scatters diffraction system and dynamic mechanical thermal analyzer. The effect of heat treatment and deformation on damping capacity and microstructure of rolled CuMn50 alloy was study.The effect of different cooling rates and aging time on the manganese-copper alloy microstructure and damping capacity were researched. The damping capacity of rolled CuMn50 alloy decreased with the cooling rate increasing, the slow cooling rate is conducive to the production of manganese-rich, played a role in aging. After aged at 420℃for different time, the damping capacity of furnace cooling specimens is further increased, however, aging time did not affect the damping properties of the sample. After aged at 420℃for different time, with the aging time increases, the grain first becomes coarse, followed by precipitation of second phaseα-mn, and the damping capacity of water cooling specimens increased to the peak value first and then slightly reduced with the aging time increasing. When the aging temperature is about 420℃,the aging time is about 8h,the best damping capacity of water cooling specimens is obtained.The microstructure and damping properties of the manganese-copper alloy by thermal cycling treatment process were researched. In the tissue of thermal cycle 10 times samples, plate martensite twins became thinner, and the precipitation of theα-Mn deposits, these make the damping properties of the thermal cycle 10 times sample dropped significantly. In the thermal cycle 30 times sampleα-Mn-rich manganese deposits formed martensite, the damping values higher than the thermal cycle 10 times sample.The microstructure and damping capacity of pre-deformation on the Mn-Cu alloy were study. The amplitude-damping properties of pre-deformed samples vary unsignificantly, The temperature-damping performance of the pre-deformation sample changes significantly with the pre-deformation increase, due to the low manganese content, induced martensite formation is not much, so the damping properties of the alloy also increased unsignificantly. With the further increase of pre-deformation, the twin martensite gradually increased, making the manganese-copper alloy high emerge the low-temperature relaxation peak twins.With the number of bending deformation increase, the applied stress induced the formation of martensite, makes martensite film contact with each other and reduce the number of martensite-parent phase interfaces, mobility would be also reduced, leading to damping capacity decreased slightly. When further increasing the number of bending deformation, martensite produced the small angle grain boundaries and twins and other sub-structure near the phase transition temperature, the mobility of sub-structure contribute to damping properties of the alloy,and make the damping performance of the alloy (near the martensitic transformation) improve at 90℃.