【作者】 袁为进；

【导师】 雷玉成；

【作者基本信息】 江苏大学 ， 材料加工， 2006， 硕士

【摘要】 SiC颗粒增强铝金属基复合材料（简称SiCp／Al金属基复合材料），具有比强度高、比模量高、膨胀系数低、耐磨性良好等优异的综合性能，在航空、航天、汽车、微电子等工业领域有广阔的应用前景。焊接技术是SiCp／Al金属基复合材料工业应用进程中必须解决的关键制造技术问题之一。熔化焊是所有焊接方法中应用范围最广、适应性最强、操作最简便、工艺最成熟的焊接方法，但SiCp／Al金属基复合材料在熔化焊接过程中，增强相SiC颗粒严重溶解并在焊缝中凝固析出粗大的针状有害相Al₄C₃，造成焊缝力学性能尤其是韧性严重下降。因此，抑制针状有害相Al₄C₃在焊缝中的形成是SiCp／Al金属基复合材料实现熔化焊接的关键问题。 为抑制针状有害相Al₄C₃在焊缝中的形成，本文提出了SiCp／Al金属基复合材料焊缝“原位”合金化等离子弧焊接新方法，以Ar+N₂为离子气、Ar为保护气，以强碳化物形成元素Ti作为合金元素，在等离子弧焊机脉冲电流下，对SiCp／6061Al金属基复合材料进行焊缝“原位”合金化焊接，研究了合金化元素Ti在焊缝中的添加量以及等离子弧焊接工艺参数对焊缝显微组织及接头性能的影响。结果表明：在等离子弧脉冲电流焊接条件下，用强碳化物形成元素Ti作为合金元素对SiCp／6061Al金属基复合材料进行焊缝“原位”合金化等离子弧焊接，完全抑制了针状有害相Al₄C₃在焊缝中形成，并获得了组织致密、均匀、并有TiN、AlN、TiC、Ti₅Si₃、Al₃Ti等金属化合物为增强相的“原位”复合材料焊缝显微组织。更多还原

【Abstract】 SiC particle reinforced aluminum metal matrix composites（SiCp/Al MMCs） are widely applied in aerospace, transportation and electronic industries due to their excellent combinations of high specific strength, high specific stiffness, low coefficient of thermal expansion and excellent wear resistance, Development of reliable and economic joining techniques is of significant importance for the successful commercialization of SiCp/Al MMCs, because joining to other components made of similar composites and other structural metallic materials is often necessary when practically applied as structural components in mechanical systems or structures. However, due to the severe heterogeneity of the material constitution and the great difference in both physical and chemical properties between the reinforcing SiC particles and the aluminum alloy matrix, joining of SiCp/Al MMCs especially when made of powder metallurgical routes has been remaining as a difficult challenging technological problem. The most serious problems are the dissolution of SiC particles and subsequent formation of the needle-like detrimental phases of Al₄C₃ during fusion-welding process. The formation of the needle-like aluminum carbides is very deleterious to the mechanical properties of the weld because the very brittle aluminum carbide in needle-like morphologies greatly deteriorates the ductility and reduces fracture toughness. Moreover, the aluminum carbide is susceptible even to moisture corrosion, greatly reducing the corrosion resistance of the weld. It is still almost impossible to completely prevent the decomposition of SiC reinforcements and the subsequent formation of the detrimental Al₄C₃ phases during fusion-welding even if the processing parameters was carefully optimized. Therefore, preventing the formation of the harmful aluminum carbides during fusion-welding process is of crucial importance for successful welding of SiCp/Al MMCs.’In-situ’ weld-alloying/plasma arc welding with Ar and N₂ as ionized gas, Ar as fielded gas, and titanium as the alloying element is utilized to join a SiCp/6061Al MMC in order to prevent the formation of the needle-like harmful Al₄C₃ phases in the weld. Microstructure of the weld is characterized by XRD,OM,SEM and EDS as functions of alloying element content and plasma arc welding processing parameters. Microhardness and tensile properties of the weld are evaluated. Results show that the更多还原