Al-Mg-Sc合金粉末激光定向沉积修复Al-Zn-Mg-Cu铝合金基板的组织及力学性能

Microstructure and mechanical property of Al-Zn-Mg-Cu aluminum alloy substrate repaired by laser directed energy deposition with Al-Mg-Sc alloy powder

激光增材修复技术对节约成本、提升材料服役性能具有重大战略意义,本文采用能量沉积方法对预设槽的Al-Zn-Mg-Cu铝合金基板进行激光修复研究。借助扫描电镜、电子背散射衍射、力学万能试验机等设备对Al-Zn-Mg-Cu铝合金试样修复后组织演化、冶金缺陷、力学性能的变化进行研究。结果表明:激光扫描间距增大易产生裂纹;激光能量输入增大,修复区的孔洞数量增多,且孔洞的形成与Mg的蒸发有关。在部分熔化区和修复区内部熔池边界析出的Al_(3)(Sc,Zr)粒子起到晶粒细化的作用。修复区内部与修复区边界处晶粒取向有明显的差别,修复区内部晶粒取向随机而修复区边界处晶粒取向较为一致。拉伸试样大多断裂于受激光热循环影响的母材区域,在扫描速率为600 mm/min,扫描间距为0.8 mm时拉伸样断裂于修复区内部,试样断口存在一定数量的孔洞。

Laser additive repair technologyis of great strategic significance to save cost and improve service performance of materials. In this paper, laser directional energy deposition method was used to study the laser repair of Al-Zn-Mg-Cu aluminum alloy substrate in preset slots. After repairing, the microstructure evolution, metallurgical defects and mechanical properties of Al-Zn-Mg-Cu aluminum alloy were studied by means of scanning electron microscopy, electron backscatter diffraction and universal mechanical testing machine. The results show that the crack is easy to occur when the laser scanning distance increases in repair zone. With the increase of laser energy input, the number of holes in the repair zone increases, and the formation of holes is related to the evaporation of Mg. The Al_(3)(Sc,Zr) particles precipitate in the partial melting zone and the boundary of the molten pool in the repaired zone.The Al_(3)(Sc,Zr) particles play a role of grain refinement. The grain orientation of the zone between the interior and boundary of repair zone is different obviously. The grain orientation of the repaired zone is random while that of the boundary of repair zoneis consistent.Most of the tensile samples fracture in the substrate region that is thermally cycled by the laser. When the scanning rate is 600 mm/min and the scanning spacing is 0.8 mm, the tensile samples fracture in the repaired zone, and there are a certain number of holes in the fracture of the sample.