【摘要】 研究了航空航天5B70铝合金真空电子束焊接接头的显微组织演变和力学性能。采用X射线衍射、扫描电子显微镜和电子背散射衍射对相组成、显微组织演变、晶粒尺寸、晶界密度和织构变化进行了定量分析。熔合区(FZ)由等轴胞状晶组成，在熔合区和热影响区(HAZ)之间的过渡区(TZ)形成约20μm厚的细晶层。热影响区与基材(BM)非常相似，保留了原始的轧制组织。力学性能测试表明，TZ中的细晶层具有最高的纳米硬度，而FZ的显微硬度最低。焊接接头试样的屈服强度、极限抗拉强度和断裂伸长率均低于BM，其主要受晶粒尺寸和析出相分布的影响。更多还原

【Abstract】 The microstructural evolution and mechanical properties of a vacuum electron beam welded aerospace 5B70 aluminum alloy joint were studied. Quantitative analyses of the phase composition, microstructural evolution, grain size, grain boundary density, and texture changes were performed by X-ray diffraction, scanning electron microscopy, and electron backscatter diffraction. The fusion zone(FZ) comprises equiaxed cellular crystals, and a fine ～20 μm-thick crystal layer forms in the transition zone(TZ) between the FZ and heat affected zone(HAZ). The HAZ closely resembles the base material(BM), retaining the original rolling microstructure. Mechanical property testing shows that the fine-grained layer in the TZ exhibits the highest nanohardness, with the FZ corresponding to the lowest microhardness. The welded-joint sample has lower yield strength, ultimate tensile strength, and elongation after fracture than the BM. These reductions of mechanical properties are primarily influenced by the grain size and distribution of the precipitated phases.更多还原