稀土改性高强铝微桁架激光增材制造工艺调控

微桁架夹芯板点阵轻量化结构在航空航天领域有重要应用，选区激光熔化（SLM）增材制造技术可克服传统工艺局限性，高质量一体化成形复杂点阵结构。以稀土Sc改性高强Al-Mg合金为对象，采用SLM工艺对其进行工艺优化试验，并基于优化结果对微桁架夹芯板开展一体化成形工艺调控研究。研究结果表明：SLM成形Al-Mg-Sc-Zr合金表面质量、冶金缺陷等随激光参数发生显著变化，在激光功率400 W、扫描速度800 mm/s的条件下获得较高表面质量（粗糙度为13.2 μm）及致密度（相对密度为99.5%）。当扫描速度较低时试件熔池底部形成一次Al₃Sc析出相，而当扫描速度过高时因凝固速度过快析出相减少，导致试件显微硬度降低。在优化工艺区间内，随激光扫描速度增加SLM成形Al-Mg-Sc-Zr微桁架夹芯板粘粉比例下降，构件质量随之减轻；水平方向构件尺寸精度、桁架微杆成形精度均随扫描速度增加而增加。

Process optimization of additive manufactured sandwich panel structure using rare earth element modified high-performance Al alloy

The lightweight sandwich panel structure shows great potential in aerospace. The Selective Laser Melting (SLM) technology can overcome the limitations of traditional technology and produce the complex lattice structure with high quality. Rare earth element Sc modified Al-Mg alloy was applied as the raw material, and optimization of SLM processing of the Al-Mg-Sc-Zr alloy was conducted. Based on the optimization, SLM processing of Al-Mg-Sc-Zr sandwich panel structure was performed. Results show that the surface quality and metallurgical defects of the Al-Mg-Sc-Zr specimens processed by SLM were highly related to laser parameters. The superior surface morphology (roughness is 13.2 μm) and maximum relative density (99.5%) were obtained with laser power of 400 W and laser scan speed of 800 mm/s. When the scanning speed is low, Al₃Sc precipitations are formed at the bottom of the molten pool of the specimen, and when the scanning speed is too high, the precipitation phase decreases due to the too fast solidification speed, resulting in a decrease in the microhardness of the specimen. With the optimized process parameters, as the laser scan speed increased, the powder stickiness decreased and the weight of the Al-Mg-Sc-Zr sandwich panel structure processed by SLM decreased. The dimensional accuracy of horizontal components and the forming accuracy of truss micro-rods all increase with the increase of scanning speed.