【作者】 凌闯；

【导师】 王敬丰；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2011， 硕士

【摘要】 本文针对锰铜合金存在的阻尼性能低和阻尼性能延时变劣等主要问题,提出了本文的研究内容和技术路线。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电子背散射衍射系统(EBSD)和动态机械热分析仪(DMA)等测试方法,研究了热处理和变形工艺对轧制态CuMn50合金的微观组织和阻尼性能的影响。研究840℃保温0.5h后不同冷速及后续时效时间对锰铜合金微观结构和阻尼性能的影响。结果表明:随着冷速提高,阻尼性能降低,缓慢冷却有利于富锰区的产生,起到了时效的作用,使合金具有较高的阻尼性能;炉冷试样时效后,阻尼性能进一步提高,时效时间对炉冷试样的微观结构和阻尼性能几乎没有影响;水冷试样时效后,随着时效时间的增大,合金的晶粒先变得粗大随后析出第二相α-Mn,阻尼性能先增大到峰值随后略为减低,420℃时效8h后,合金的阻尼性能达到最好。通过研究锰铜合金热循环处理工艺试样的微观结构和阻尼性能,发现热循环10次试样的组织中,片状马氏体孪晶片层变细,而且沉淀析出了α-Mn沉淀物,从而使得热循环10次试样的阻尼性能大幅下降;与热循环10次相比,热循环30次试样在测试温度范围内合金的阻尼值增大,这是因为在α-Mn沉淀物形成的富锰区产生了新的马氏体。研究了预变形对锰铜合金微观结构和阻尼性能的影响。锰铜合金的振幅-阻尼曲线随预变形量的变化不大。预变性试样的微观结构和温度-阻尼曲线结果表明,随着预变形的增大,由于锰含量偏低,诱发生成的新马氏体并不多,所以合金的阻尼性能也增加不大;随着预变形的进一步增大,马氏体相变孪晶逐渐增多,使得锰铜合金出现了明显的低温孪晶弛豫峰。随着弯曲变形次数的增加,首先在外加应力的作用下,诱发形成马氏体,马氏体片的相互接触使得马氏体与母相界面的数量减少,可动性也会降低,从而导致内耗略微下降;当弯曲变形次数进一步增大,马氏体组织在相变温度附近产生小角度晶界和孪晶等亚结构,这些亚结构的可动性对合金的阻尼性能做出贡献,使得合金在90℃(马氏体相变点附近)的阻尼性能提高。更多还原

【Abstract】 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℃.更多还原