热处理对30%SiCp/Al复合材料阻尼性能的影响

Effect of heat treatment on damping capacity of 30%SiCp/Al composites

采用真空热压烧结法制备30%SiCp/2024Al复合材料以改善2024铝合金的阻尼性能,通过扫描电镜(SEM)、X射线衍射(XRD)、能谱仪(EDS)、高分辨透射电镜(HRTEM)等对复合材料热处理前后的微观组织进行了表征。采用动态热机械分析仪(DMA)研究其热处理前后的阻尼特性。结果表明:热压烧结制备的复合材料界面结合良好,无界面反应,存在许多粗大析出相颗粒,经热处理之后,纳米析出相弥散分布在基体中,可提高复合材料的阻尼性能。30%SiCp/Al复合材料的阻尼性能随温度和应变量的升高而增大,储能模量随温度和应变量的升高而降低。热处理态复合材料中大量弥散的纳米析出相颗粒增加了界面的数量,使界面阻尼增加。复合材料的阻尼机制为位错阻尼、晶界阻尼和界面阻尼。晶界阻尼对温度敏感,大量的界面、晶界可以明显改善复合材料的高温(大于250℃)储能模量,从而改善30%SiCp/Al复合材料的阻尼性能。

30%SiCp/2024Al composites were prepared by vacuum hot pressing sintering to improve the damping capacity of 2024 aluminum alloy.Microstructure of the composites before and after heat treatment was characterized by means of scanning electron microscopy(SEM),X-ray diffraction(XRD),energy dispersive spectroscopy(EDS)analysis,and high resolution transmission electron microscopy(HRTEM),and dynamic thermal mechanical analyzer(DMA)was used to study the damping characteristics of the composites before and after heat treatment.The results show that the composites prepared by hot pressing sintering have good interface bonding,no interface reaction,and there are many coarse precipitated particles.After heat treatment,the nano precipitates are dispersed in the matrix,which can improve the damping capacity of the composites.The damping capacity of the 30%SiCp/Al composites increases with the increase of temperature and strain,and the storage modulus decreases with the increase of temperature and strain.A large number of dispersed nano precipitates in the heat-treated composites increase the number of interfaces and the damping of interfaces.The damping mechanisms of the composites are dislocation damping,grain boundary damping and interface damping.Grain boundary damping is sensitive to temperature.A large number of interfaces and grain boundaries can significantly improve the storage modulus of the composites at high temperature(more than 250℃),thereby improving the damping capacity of the 30%SiCp/Al composites.