低温下钎焊铝合金能够避免母材受热发生软化。研究了使用纯Sn超声钎焊纯Al时,初晶α(Al)对Al/Sn界面显微组织和结合强度的影响。结果表明,在液态Sn中,α(Al)的{111}面的表面能和生长速度最小,因此,析出的初晶α(Al)的形态为{111}面包围的正八面体。超声能够起到提高形核率并细化初晶α(Al)颗粒的作用。在较长的超声和保温时间下,Al/Sn界面会析出大量八面体初晶α(Al)颗粒,使界面呈现出一种起伏不平的形貌,增加了界面实际结合面积和咬合作用。超声作用40s,保温10min时界面的结合强度达到63MPa。 Brazing aluminum alloy at low temperature can prevent the base metal from softening due to heat. The effect of primary α (Al) on the microstructure and bonding strength of Al / Sn interface was studied when using pure Sn ultrasonic brazing pure Al. The results show that the surface energy and growth rate of the {111} plane of α (Al) is the smallest in the liquid Sn. Therefore, the morphology of the precipitated primary α (Al) is a regular octahedron surrounded by the {111} plane. Ultrasound can improve the nucleation rate and refine primary α (Al) particles. Under long ultrasonic and holding time, a large amount of octahedral α (Al) particles precipitated in Al / Sn interface, which presented an undulating appearance and increased the actual bonding area and occlusal effect. Ultrasound effect 40s, 10min when the interface bonding strength reaches 63MPa.