泡沫铝氮气保护炉中钎焊界面结构及力学性能

Interface structure of N2-shielded furnace brazing of Al foam and its mechanical properties

对泡沫铝板采用铝基钎料炉中钎焊界面结构进行试验研究,采用SEM和显微镜观察分析钎缝组织,EDS分析界面元素分布,并用计算机层析扫描技术(X-CT)等对钎焊界面孔结构进行观察并重构了界面三维图像,在接触界面模型基础上分析钎焊接头力学性能和影响因素。结果表明,钎焊方法未改变钎缝孔结构;钎缝界面由端面胞壁棱接触相交点组成,未形成持续膜层;钎缝主要由边缘区αAl枝状晶组织和中心区的Al-Si共晶组织组成;钎焊接头强度与母材相当并随孔隙率增大而降低;胞棱数量越多钎着面积越大,接头强度接近母材强度,高孔隙率(>88%)泡沫铝接触界面模型中的胞棱数量与实测值相吻合。

N2-shielded furnace brazing of Al foam was studied experimentally and the microstructure of brazing interface and elements distribution were analyzed by SEM,EDS and optical microscope.Furthermore,morphology of brazing zone was observed by scan model of X-CT and the 3D image of interface was reconstructed.The mechanical properties and the relationship between joint strength and porosity of Al foam were also investigated.The results show that the brazing method does not change the pore structures of Al foam in brazing zone.The brazing interface consists of the intersection points between cell walls of two Al foams and the microstructure in the middle of brazing zone is Al-Si eutectic while near the interface is the αAl dendrite.The tensile strength of joint closes to that of the base.Brazed area of interface increases with increasing of the Al foam plateau amount,which matches well with the theoretic calculation results when the porosity is over 88%.