(1. 哈爾濱工業(yè)大學 先進焊接與連接國家重點實驗室，哈爾濱 150001；
2. 哈爾濱工業(yè)大學 復(fù)合材料與結(jié)構(gòu)研究所，哈爾濱 150080)
摘 要: 研究超聲波作用下SiCp/Al復(fù)合材料焊縫的微觀組織特征，并采用SEM對室溫下焊縫的原位拉伸斷裂特性過程及斷口形貌進行觀察分析。結(jié)果表明，在焊接不同階段經(jīng)超聲波處理，可有效地控制焊縫的微觀組織。在拉伸應(yīng)力作用下所有焊縫在沒有觀察到明顯裂紋生成之前瞬間發(fā)生斷裂，呈現(xiàn)脆性斷裂的特征。當焊縫中無SiC顆粒時，焊縫中發(fā)達的Zn-Al共晶相為焊縫的薄弱相，是裂紋萌生的部位，且是裂紋擴展的主要路徑。當母材中的SiC顆粒遷移到焊縫中時，主要聚集于共晶相中，SiC顆粒和共晶組織的結(jié)合界面是微裂紋萌生的部位，裂紋主要沿著共晶組織擴展，在強大的脆性斷裂慣性作用下，擴展路徑上較多的先共晶相β(Zn)發(fā)生解理斷裂，先共晶相α(Al)具有明顯的抗裂作用。
關(guān)鍵字: 鋁基復(fù)合材料；焊縫；微觀組織；斷裂行為；原位觀察
（1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;
2. Center for Composite Materials and Structure, Harbin Institute of Technology, Har）
Abstract:The microstructural characteristics of ultrasonic assisted fabricating bonds in SiCp/Al composites were investigated and the in-situ dynamic tensile process and the fracture surface at room temperature of the resultant bonds were observed by scanning electric microscopy (SEM). The results show that the bond microstructure can be effectively controlled by the application of ultrasonic vibration at different bonding stages. All the bonds rupture instantaneously under the tensile stress before obvious cracks are observed, which belong to a brittle fracture mode. When the bond is free of SiC particles, the flourishing Zn-Al eutectics are weak and serve as the crack sources and the main path of crack propagation. When SiC particles are present in the bond, which are transferred from the base metal and agglomerate in the Zn-Al eutectics, micro-crack initiates at the SiC/eutectics interface and mainly propagates along the Zn-Al eutectics, with a number of cleavage fracture of primary phase β(Zn) occurring in the crack propagation path under the rupture inertia. Primary phase α(Al) has a significant role in crack resistance.
Key words: aluminum metal matrix composites; bond; microstructure; fracture behavior; in-situ observation
