深冷处理对15%SiC_(p)/2009铝基复合材料组织与力学性能的影响

Effect of cryogenic treatment on microstructure and mechanical properties of 15%SiC_(p)/2009 aluminum matrix composite

采用硬度测试、X射线衍射物相分析、力学性能测试和透射电镜(TEM)观测等方式,研究长时间深冷处理对固溶-时效处理的碳化硅颗粒增强铝基复合材料组织与性能的影响,并从材料组织角度分析了深冷处理改善碳化硅颗粒增强铝基复合材料力学性能的机理。结果表明,与未经深冷处理的时效态铝基复合材料相比,经深冷处理的铝基复合材料试样提前2 h达到硬度峰值,约211.7 HV0.1,且整个时效阶段硬度均高于未深冷处理试样;时效早期(欠时效)阶段,经深冷时效处理的颗粒增强铝基复合材料试样组织中存在细小且均匀分布的针状析出相,而对比时效试样组织未见明显析出现象;过时效阶段中,深冷-时效试样与时效试样均存在大尺寸析出相,且后者析出相尺寸、分布明显不均匀,但两者的力学性能随时效时间的延长而趋于近乎一致,说明深冷处理的影响降低。

Effect of long time cryogenic treatment on microstructure and mechanical properties of solution treated and aged SiC particles reinforced aluminum matrix composite was studied by means of hardness tests,X-ray diffraction analysis,mechanical tests and transmission electron microscope(TEM)observation.The mechanism of cryogenic treatment improving mechanical properties of the tested composite was analyzed in terms of microstructure.The results show that the hardness of the aged aluminum matrix composite with cryogenic treatment reaches the peak value(about 211.7 HV0.1)by 2 h earlier than that without cryogenic treatment.During the whole aging stages,the hardness of aged specimens with cryogenic treatment is higher than that without cryogenic treatment.During the under-aging stage,there are fine and uniformly distributed needle-like precipitates in microstructure of the specimens with cryogenic treatment,which is not apparent for that without cryogenic treatment.During the over-aging stage,large-size precipitates appear in both groups of the specimens with and without cryogenic treatment,the precipitate size and distribution are obviously uneven in that without cryogenic treatment,but the mechanical properties of both groups tend to be almost the same with the increase of aging time,as the effect of cryogenic treatment on mechanical properties of aluminum matrix composites is declined.