激光粉末床增材制造粗粒径AlMgScZr合金工艺与性能研究

Process Optimization and Mechanical Properties of AlMgScZr Alloy Fabricated by Laser Powder Bed Fusion Using Coarse Powder

摘要:

随着激光粉末床（LPBF）增材制造技术发展，如何高效利用超出常规粒径（15~53 μm）范围的粉末以提高原材料利用率，成为亟待解决的关键问题。本研究聚焦于粗粒径（53~150 μm）AlMgScZr合金粉末在激光粉末床增材制造过程的工艺调控、微观组织及力学性能特征。基于控制变量法研究工艺参数对致密度、缺陷、微观组织及力学性能的影响。结果发现粗粒径AlMgScZr合金工艺窗口较窄，其成形稳定性对工艺波动高度敏感，优化后工艺参数为：层厚100 μm，功率450 W，扫描速率900 mm/s，此时致密度为99.3%±0.2%。熔合线附近为细密的等轴晶，熔池内为柱状晶，未观察到明显的第二相颗粒。打印态样品显微硬度为99.7±8.9 HV_0.1，抗拉强度为336.5±8.0 MPa，延伸率为12.7%±0.4%。

Abstract:

With the advancement of laser powder bed fusion (LPBF) additive manufacturing, efficient utilization of powders outside the conventional particle size range (15–53 μm) has become critical to improving powder efficiency. This study investigated process optimization, microstructure, and mechanical properties of coarse AlMgScZr alloy powders (53–150 μm) in LPBF. The controlled variable method was employed to analyze parameter effects on density, defects, microstructure, and mechanical properties. Results show that the coarse powder exhibits a narrow process window with high sensitivity of forming stability to parameter fluctuations. The optimized parameters are a layer thickness of 100 μm, a laser power of 450 W, and a scanning speed of 900 mm/s. This parameter set achieves a relative density of 99.3%±0.2%. Microstructural analysis reveals fine equiaxed grains near fusion boundaries transitioning to columnar grains within molten pools, without observable secondary precipitates. The as-printed samples show a microhardness of 99.7±8.9 HV_0.1, tensile strength of 336.5±8.0 MPa, and elongation of 12.7%±0.4%.