纳米SiCp含量对超声方法制备的SiCp/A356复合材料组织和性能的影响

摘要

nano-SiCp/A356 composites with different nano-SiCp contents were prepared by squeeze casting after ultrasonic treatment (UT). The effects of SiCp content on the microstructure and mechanical properties of the nanocomposites were investigated. The results show that with the addition of nano-SiCp, the microstructure of nanocomposites is obviously refined, the morphology of theα(Al) grains transforms from coarse dendrites to rosette crystals, and long acicular eutectic Si phases are shortened and rounded. The mechanical properties of 0.5％, 1％ and 2％ (mass fraction) SiCp/A356 nanocomposites are improved continuously with the increase of nano-SiCp content. Especially, when the SiCp content is 2％, the tensile strength, yield strength and elongation are 259 MPa, 144 MPa and 5.3％, which are increased by 19％, 69％ and 15％, respectively, compared with those of the matrix alloy. The improvement of strength is attributed to mechanisms of Hall-Petch strengthening and Orowan strengthening.%采用超声处理和挤压铸造制备具有不同纳米SiC颗粒含量的复合材料,并研究SiCp含量对纳米复合材料显微组织和力学性能的影响.结果表明,随着纳米颗粒的加入,显微组织明显细化,α(Al)晶粒形貌由粗大枝晶向玫瑰晶转变,长针状共晶硅逐渐变短并且圆整.随着颗粒含量的增加,复合材料的抗拉强度、屈服强度和伸长率均持续增加.特别是,当SiC加入量达到2％(质量分数)时,抗拉强度、屈服强度和伸长率分别为259 MPa、144 MPa和5.3％,与基体合金相比分别增加19％、69％和15％.强度的提升是由于Hall-Petch强化和Orowan强化.