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利用分离式霍普金森压杆(SHPB)研究了40%体积分数的SiCP/2024Al复合材料和基体材料2024Al在不同应变率下的动态压缩性能。在高应变率动态压缩时该复合材料与2024Al均表现出应变率不敏感,复合材料屈服应力高于2024Al;与2024Al的应变硬化性能不同,复合材料表现出应变软化性能。利用扫描电镜(SEM)观察动态压缩后复合材料试件的微观组织,发现试件内部出现一些孔洞、微裂纹以及一些增强颗粒的破碎等损伤现象,并且在较高应变率下基体呈现出明显的热软化甚至发生局部熔化,由此判断,在高应变率下SiCP/2024Al复合材料宏观应变软化的机制为内部损伤及基体热软化。将SiCP/2024Al复合材料与2024Al经400℃下烧蚀3 h后自由冷却至室温,利用SHPB再次进行测试,与烧蚀前的测试结果相比,2024Al的性能明显下降,而复合材料的性能变化较小,表现出比基体材料更好的抗高温稳定性能。
The dynamic compressibility of 40% volume fraction SiCP / 2024Al composites and 2024 Al matrix at different strain rates was investigated by using split Hopkinson pressure bar (SHPB). The composites show a strain rate insensitivity to 2024Al at high strain rate dynamic compression, and the yield stress of the composites is higher than 2024Al. The strain hardening properties of the composites are different from those of 2024Al, and the composites show strain softening properties. Scanning electron microscopy (SEM) was used to observe the microstructures of the dynamically-compressed composite specimens. It was found that some pores, micro-cracks and some damage phenomena such as broken particles were observed in the specimens, and the matrix showed obvious The results show that the mechanism of macroscopic strain softening of SiCP / 2024Al composites under high strain rate is internal damage and matrix softening. The SiCP / 2024Al composites and 2024Al were ablated at 400 ℃ for 3 h, then cooled to room temperature and re-tested by SHPB. Compared with the pre-ablation results, the properties of 2024Al obviously decreased, while the properties of the composites Smaller, showing better high temperature stability than the matrix material.