采用搅拌摩擦加工(friction stir processing, FSP)对 6063 铝合金进行了扩散焊接的焊前表面处理。 实验结果表明，经 FSP 处理后表面形成细晶层，呈现出清晰梯度组织结构，截面分为搅拌区、热机械影响区和母材区 3 个区域。 为评估表面处理方法的优化效果，对比了不同表面处理方法(无 FSP、单侧 FSP、双侧 FSP)对扩散焊接头组织和力学性能

的影响，发现未经过 FSP 处理，界面处显著存在大量未焊合缺陷 ；相比之下，单侧 FSP 处理后的界面愈合效果较未经FSP 处理有一定提高，界面孔洞为扁平状，接头两侧晶粒尺寸差异较大；而经双侧 FSP 处理时，界面结合效果得到极大改善，除少量颗粒状孔洞，其余部分均焊合，分析其孔洞为界面处的 Mg2Si 氧化物颗粒经腐蚀后脱落形成。 进一步地，针对双侧 FSP 表面预处理的接头，在 570 ℃-4MPa 工艺参数条件下，开展了保温时间对接头力学性能的影响研究 ，结果表明，当保温时间由 30 min 延长到 90 min 时，尽管屈服强度变化不大，但抗拉强度显著增加，最高可达 111.8 MPa(达到母材强度的 85.3%)，同时伸长率也随时间的延长而增大，最高为 20.1%。 断口形貌分析同步揭示了断裂模式转变，随着保温时间增加，韧窝数量增加，表明断裂方式从脆性断裂逐渐演变为韧性断裂。

Friction stir processing (FSP) was adopted to carry out the preweld surface treatment of diffusion welding on 6063 aluminium alloy. The experimental results reveals that after FSP, a fine-grained layer formed on the surface, resulting in a clear gradient microstructure. The cross-section is divided into three areas: the stirring zone, the thermal mechanical influence zone and the base material zone. To evaluate the optimization effect of surface treatment methods, the influences of different surface treatment methods (no FSP, unilateral FSP, and bilateral FSP) on the microstructure and mechanical properties of diffusion-welded joints were compared. Without FSP treatment, many unwelded defects are significantly formed at the interface. In contrast, the interface healing effect after the unilateral FSP treatment improves to a certain extent compared with that without the FSP treatment. The interface holes are flat, and the grain sizes on both sides of the joint are quite different. When the samples are subjected to bilateral FSP, the interfacial bonding effect is greatly improved. Except for a few granular holes, the remaining holes are welded together. The holes are formed by the shedding of Mg2Si oxide particles at the interface after corrosion. Furthermore, for joints subjected to bilateral FSP surface pretreatment, a study on the influence of holding time on the mechanical properties of the joints is carried out under the process parameters of 570 ℃-4 MPa. The results show that when the holding time is extended from 30 min to 90 min, although the yield strength changes little, the tensile strength increases significantly, reaching up to 111.8 MPa (85.3% of the strength of the base material), and at the same time, the elongation also increases with increasing time, reaching 20.1%. The analysis of the fracture morphology simultaneously reveals the transformation of the fracture mode. With increasing holding time, the number of dimples increases, indicating that the fracture mode gradually evolves from brittle fracture to ductile fracture.