Zhang Mingli, Pan Ran, Liu Baosheng, Gu Kaixuan, Weng Zeju, Cui Chen, Wang Junjie
CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Beijing 100190, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Materials (Basel). 2023 Jan 1;16(1):396. doi: 10.3390/ma16010396.
Aluminum matrix composites have been widely used in aerospace and automotive fields due to their excellent physical properties. Cryogenic treatment was successfully adopted to improve the performance of aluminum alloy components, while its effect and mechanism on the aluminum matrix composite remained unclear. In this work, the effects of cryogenic treatment on the microstructure evolution and mechanical properties of 15%SiCp/2009 aluminum matrix composites were systematically investigated by means of Thermoelectric Power (TEP), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that TEP measurement can be an effective method for evaluating the precipitation characteristics of 15%SiCp/2009 aluminum matrix composites during aging. The addition of cryogenic treatment after solution and before aging treatment promoted the precipitation from the beginning stage of aging. Furthermore, the aging time for the maximum precipitation of the θ″ phase was about 4 h advanced, as the conduction of cryogenic treatment accelerates the aging kinetics. This was attributed to the great difference in the linear expansion coefficient between the aluminum alloy matrix and SiC-reinforced particles, which could induce high internal stress in their boundaries for precipitation. Moreover, the lattice contraction of the aluminum alloy matrix during cryogenic treatment led to the increase in dislocation density and micro defects near the boundaries, thus providing more nucleation sites for precipitation during the aging treatment. After undergoing artificial aging treatment for 20 h, the increase in dispersive, distributed precipitates after cryogenic treatment improved the hardness and yield strength by 4% and 16 MPa, respectively.
铝基复合材料因其优异的物理性能而在航空航天和汽车领域得到广泛应用。低温处理已成功应用于改善铝合金部件的性能，但其对铝基复合材料的影响及作用机制尚不清楚。在本工作中，通过热电功率（TEP）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）系统研究了低温处理对15%SiCp/2009铝基复合材料微观结构演变和力学性能的影响。结果表明，TEP测量可作为评估15%SiCp/2009铝基复合材料时效过程中析出特性的有效方法。在固溶处理后和时效处理前进行低温处理，促进了时效初期的析出。此外，由于低温处理加速了时效动力学，θ″相最大析出量的时效时间提前了约4小时。这归因于铝合金基体与SiC增强颗粒之间的线膨胀系数差异很大，这会在它们的界面处引起高内应力以促进析出。此外，低温处理过程中铝合金基体的晶格收缩导致界面附近位错密度和微缺陷增加，从而为时效处理过程中的析出提供了更多形核位点。经过20小时的人工时效处理后，低温处理后弥散分布的析出相增加，使硬度和屈服强度分别提高了4%和16MPa。
