钎焊温度对6063铝合金氮气钎焊接头组织与性能的影响OA

With the increasing demand for high-efficiency and reliable joining of aluminum alloy structural components in avionics and related fields,nitrogen brazing of 6063 aluminum alloy still suffers from insufficient wetting/spreading and joint defects.In this study,6063 aluminum alloy joints were fabricated via an Al-Si filler metal at brazing temperatures of 605～625 ℃.The effects of brazing temperature on the wetting behavior,microstructure evolution,grain boundary characteristics,and shear strength were systematically investigated.The results show that during the holding stage at 605 ℃,the contact angle steadily decreased from approximately 92.9° to a stable value of 65.8° over about 1200s,indicating diffusion-dominated wetting behavior.With increasing brazing temperature,the overall amount of lack-of-bonding regions and pore defects in the brazed seam decreased,leading to significantly improved joint densification.The joint microstructure mainly consisted of α-Al,β-Al5FeSi,and Si phases.EBSD analyses revealed that the β-Al5FeSi phase exerted a significant pinning effect on grain boundary migration,allowing the precipitate-enriched regions to retain finer grains and exhibit higher KAM values.Meanwhile,increasing temperature promoted a higher fraction of high-angle grain boundaries(about 61.6％at 620℃),leading to a more stable and homogenized joint structure.The shear strength exhibited a rise-then-fall trend with temperature;the optimal overall performance was obtained at 615℃,where the shear strength reached 74.67MPa.