搅拌铸造SiC_p/A356复合材料的显微组织及力学性能  

Microstructure and Mechanical Properties of SiC_p/A356 Aluminum Matrix Composites Prepared by Stirring Casting

作　　者：毛成[1] 高文理[1] 苏海[1] 卢健[2] 陆政[2] 

机构地区：[1]湖南大学材料科学与工程学院 [2]北京航空材料研究院

出　　处：《特种铸造及有色合金》2010年第3期256-259,共4页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(50771043;09JJ6084);国家重点基础研究发展计划(973计划)资助项目(2008CB617608;2009CB623704)

摘　　要：采用搅拌铸造技术制备质量分数为15%的SiCp增强A356铝基复合材料,并对所制备的复合材料进行后续热挤压变形。通过金相观察(OM),扫描电镜(SEM)及力学性能测试等手段,对该复合材料显微组织与力学性能进行了研究。结果表明,所制备的复合材料铸态组织中,SiCp较均匀地分布于基体中,SiCp与Al界面处存在Si原子的富集;热挤压变形后,显微气孔等铸造缺陷明显减少,材料致密度显著提高,SiCp沿热挤压方向呈流线分布特征,颗粒均匀分散性明显提高;采用535℃×5h固溶+180℃×5h时效处理后,热挤压棒材的力学性能为:σs=370MPa,σb=225MPa,δ=5.3%,时效后析出强化相大小约为200nm,且弥散分布于基体中;断口分析表明,SiCp/A356铝基复合材料的断裂主要是由基体的塑性断裂及SiCp的断裂导致的。SiC particle reinforced A356 aluminum matrix composites with 15% in mass fraction was prepared by stirring casting,and prepared composites were deformed by hot extrusion process.Microstructure and mechanical properties of the prepared composites were investigated by OM(optical microscope),SEM(scanning electron microscope)and tensile testing.The results show that,SiC particles are distributed uniformly in the alloy matrix,and there exists the enrichment of Si atoms in the interface of SiC/Al.After hot extrusion deformation,casting defects such as porosity are distinctly decreased,resulting in the great improvement of the composites density,meanwhile,directional distribution of SiC particles along the direction of the metal plastic flowing can be observed with the increase of uniformly dispersed SiC particle.After 535℃/5 h solid solution +180℃ /5 h aging treatment,the mechanical properties of hot extruded composites in which approximately 200 nm precipitates with dispersed distribution are observed can reach 370MPa in tensile strength,225MPa in yield strength and 5.3% in elongation.Fracture mechanism of SiCp/A356 aluminum matrix composites is characterized by plastic fracture of matrix alloy and SiC particle fracture.

关 键 词：铝基复合材料 搅拌铸造 热挤压 显微组织 力学性能 

分 类 号：TG24[金属学及工艺—铸造]