【作者】 王红梅；

【导师】 李爱滨；

【作者基本信息】 哈尔滨工业大学 ， 材料科学， 2008， 硕士

【摘要】 本文以研制和开发功能结构一体化的高阻尼复合材料为目的,研究了采用粉末冶金和热挤压工艺制备的Meso-10超硬铝合金和XN-05无定形碳纤维增强的Meso-10铝基复合材料的力学与阻尼性能。利用金相显微镜(OM)和扫描电子显微镜(SEM)对复合材料中纤维的分布及拉伸断口进行微观组织观察,利用透射电子显微镜(TEM)对复合材料的界面结构和位错组态进行了分析;通过拉伸试验和硬度试验评价材料的力学性能;采用动态机械分析仪(DMA-Q800)研究材料的低频阻尼性能随应变振幅和温度的变化规律;确定材料的固溶时效工艺并研究固溶时效对材料力学和阻尼性能的影响;采用有限元法对多纤维增强铝基复合材料的室温阻尼性能进行数值模拟,并且对本文中的低模量碳纤维增强铝基复合材料的阻尼机制进行综合分析。揭示了超硬铝基复合材料低频阻尼行为的变化规律及其影响因素,为开发高阻尼、高性能铝基复合材料奠定了良好的基础。研究结果表明,碳纤维均匀地分布在Meso-10Al基体中,并且在增强体与基体之间没有发现界面反应,铝合金与碳纤维是弱界面结合。随着碳纤维体积分数的增加,复合材料力学性能逐渐下降,但由于基体材料为超硬铝合金,体积分数为10%与15%的复合材料的力学性能仍能满足工程应用的需要。对室温下挤压态材料的阻尼-应变曲线研究表明,铝合金及复合材料的阻尼性能对应变振幅表现出独立和依赖两个方面,符合G-L位错阻尼机制,频率对复合材料的阻尼-应变谱影响不大;10%和15%的复合材料具有比基体合金好的阻尼性能,25%复合材料的阻尼性能反而比基体合金的差。对阻尼-温度-频率曲线的研究表明,铝基复合材料的阻尼性能随温度的升高而增加,随频率的降低而增加,复合材料在250℃左右,均出现界面内耗峰。对固溶时效后的材料进行力学和阻尼性能测试,发现140℃时效的材料力学性能和阻尼性能改善最明显,力学性能提高35%,阻尼值增加1倍;固溶时效后复合材料在150℃(P1)和250℃(P2)左右均出现峰值,认为P1是由位错拖拽点缺陷运动造成的,P2是由晶界和界面滑移引起的,具有热激活特征。采用有限元法对多纤维增强复合材料的室温阻尼性能进行数值模拟,发现室温阻尼是基体材料在外加循环载荷的作用下,发生局部塑性变形,消耗能量造成的,符合G-L位错阻尼机制,模拟数据与试验结果很好的相符。数值模拟结合试验手段综合分析材料的微观阻尼机制发现,低温时,XN-05C/Meso-10Al复合材料以位错阻尼和增强纤维的本征阻尼为主导机制,高温时,以合金的本征阻尼和界面滑移机制为主导机制。更多还原

【Abstract】 On the purpose to research and develop structural-functional high damping composites, mechanical properties and damping capacities of superhard Meso-10 aluminum alloy and composites reinforced by amorphous carbon fibers XN-05C were investigated in the paper. The XN-05C/Meso-10Al composites and aluminum alloy were fabricated by powder metallurgy, followed by hot extrusion. The distribution of the fiber in composites and the tensile fracture were observed by Optical Micrograph (OM) and Scanner Electron Microscope (SEM).The microstructure of the reinforcement/matrix interface and the configuration of dislocations in the composites were investigated by Transmission Electron Microscope (TEM). The mechanical properties were examined by tensile and hardness tests. The strain dependent and temperature dependent low frequency damping capacities of these composites and alloys were studied by dynamic mechanical thermal analyzer (DMA-Q800). The process of solution and aging was maded and the influences on mechanical properties and damping capacities were studied after solutiont and aging treatment. The room damping capacity was simulated by FEM and damping mechanism was fully analyzed for low modul amorphous carbon fiber reinforced superhard aluminum composites. This paper revealed the low frequency damping behaviors and their influence factors of Meso-10Al alloys and composites, established a good foundation to develop high damping aluminum matrix composites.The results showed that carbon fibers were uniformly distributed in the Meso-10Al matrix. Meanwhile, no apparent reaction is found at interface between fiber and matrix, fiber and matrix were linked by weak interface. As the volume fraction increases, the mechanical property of composites decreases, but because matrix alloy was superhard aluminum alloy, so the mechanical properties of 10% and 15% composites were fulfilled for engineer application.The investigation of the curve of damping-strain amplitude at room temperatrue indicated that the curve showed strain amplitude dependent and independent regions, the curves were well interpreted by G-L dislocation model, and frequency has slight influence on the damping capacity. Compare with matrix alloy 10% and 15% composites had the better damping capacity, otherwise 25% composite had worse damping capacity. The investigation of the temperature dependent damping capacity showed that the damping capacity increased when the temperature increased or the frequency decreased. The damping peaks induced by interface slippage around 250℃were found in composites.The mechanical property and damping capacity of material were tested after solution and aging treatment, and found mechanical property and damping capacity improved best when material aging at 140oC.The mechanical property improved 30% and the damping value was two times of extruded material when material aging at 140℃Two damping peaks at 150℃and 250℃were found in composites after solution and aging treatment. It is thought that the first peak was formed by the dislocation movement dragging the point defects, and the second peak was formed by slippage of interface, and the two peaks were heat-activate.The damping capacity of multi-fiber reinforced superhard aluminum composites XN-05C/Meso-10Al was simulated dynamically by finite element method. The room damping capacity was induced by the plastic deform of matrix under cyclic outside force, and it is in good accordance with G-L theory of dislocation intemal friction, and the simulation results were in good accordance with the experiments. Through examination and simulation the damping mechanism analysis was carried out, and found that at low temperature the dominant damping mechanisms are dislocation damping and internal damping of carbon fiber, at high temperature the dominant damping mechanisms are internal damping of superhard aluminum alloy and interface sliding更多还原