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SiC含量对大尺寸铝基复合材料组织和性能的影响

Effect of SiCp content on microstructure and properties of large size aluminum matrix composites

  • 摘要: 针对航空、航天、高端电子等领域对轻量化结构材料的需求,颗粒增强铝基复合材料的应用得到了快速发展。但目前铝基复合材料研究大多集中于中小尺寸坯锭制备及分析,对大尺寸坯锭及其性能与组织的研究较少。实验采用粉末冶金工艺制备了SiCp体积分数为15%、20%和25%,基体合金为2009Al,规格为ϕ580 mm×730 mm的热压坯锭,并挤压为ϕ250 mm的挤压棒。所制备的挤压棒致密度均达到100%,颗粒分布均匀。通过XRD分析发现材料中存在少量Al2Cu和Al7Cu2Fe;通过TEM对SiCp与基体界面观察,发现SiCp与基体结合良好,无明显的界面反应。室温拉伸实验表明,复合材料强度会随SiCp体积分数增加显著提升,当SiCp体积分数为25%时,其抗拉强度为630 MPa,屈服强度为480 MPa,伸长率大于等于3%,抗拉强度和屈服强度较基体合金分别提高20%和25%。3种SiCp含量的复合材料断裂方式均以基体合金的韧性断裂和SiCp的断裂为主,并且SiCp与铝基体界面结合的高强度让SiCp起到了良好的承载作用。

     

    Abstract: In response to the demand for lightweight structural materials in aviation, aerospace, high-end electronics and other fields, the application of particle reinforced aluminum matrix composites has been rapidly developed. However, at present, most of the research on aluminum matrix composites focuses on the preparation and analysis of small and medium size ingot, and the research on large size ingot and its properties and microstructure is less. The hot pressing billets with the volume fraction of 15%, 20% and 25% SiCp, the matrix alloy of 2009Al and the size of ϕ580 mm×730 mm were prepared by powder metallurgy, and the extrusion rod was extruded to ϕ250 mm. The density of the extruded rods is 100%, and the particle distribution is uniform. A small amount of Al2Cu and Al7Cu2Fe are found by XRD analysis. The interface between SiCp and matrix was observed by TEM. It is found that SiCp and matrix are well combined, and no harmful interfacial reaction is observed. The tensile test at room temperature shows that the strength of the composite increases significantly with the increase of the volume fraction of SiCp. When the volume fraction of SiCp is 25%, the tensile strength of the composite is 630 MPa, the yield strength is 480 MPa, and the elongation is ≥3%. The tensile strength and yield strength of the composite are 20% and 25% higher than that of the matrix, respectively. The fracture modes of the three kinds of composites with SiCp content are dominated by the ductile fracture of the matrix alloy and the fracture of SiCp, and with the increase of the volume fraction of SiCp, the fracture phenomenon of SiCp increases significantly, and the fracture is more obvious, indicating that the high strength of the interface combination of SiCp and aluminum matrix makes SiCp plays a good bearing role.

     

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