高Mg含量Al-Mg-Sc-Zr合金选区激光熔化成形及力学性能研究

Processability and Mechanical Properties of High Mg-content Al-Mg-Sc-Zr Alloy Produced by Selective Laser Melting

摘要:

基于宽粒径分布粉末（2-46 μm），应用选区激光熔化（SLM）技术制备了高Mg含量Al-14.4Mg-0.33Sc-0.19Zr铝合金。系统研究了不同工艺参数和时效处理条件对合金SLM成形性、组织和力学性能的影响。结果表明，高激光功率可有效降低细粉飞溅对样品成形性的干扰，SLM成形样品的最大的相对密度为98.6%。样品显微组织由熔池边界细小等轴晶和熔池内部粗大晶粒构成，Mg含量的增加降低了样品织构和柱状晶的含量。经不同温度时效处理后，SLM成形样品的硬度先增加后降低，在350 ℃时具有最大值。SLM成形样品在350 ℃下时效处理时，硬度和压缩屈服强度均随时效时间的增加出现双峰值现象，时效1 h后样品的硬度和强度均达到最大值，分别为163±3 HV和457±10 MPa，延伸率为27±3%。样品经350 ℃长时间时效处理后，由于第二相粒子的粗化，导致样品的硬度和强度有所降低。本研究通过保留铝合金粉末的细粉区，有效提升了粉末的利用率，降低了原料成本，获得了成形性和力学性能较优的高Mg含量SLM成形Al-Mg-Sc-Zr铝合金。

Abstract:

Al-14.4Mg-0.33Sc-0.19Zr aluminium alloy with wide particle size distribution powders (2-46 μm) and high Mg-content was prepared by selective laser melting (SLM). The effects of different process parameters and aging treatment on the processability, microstructure and mechanical properties of SLM-formed Al-Mg-Sc-Zr alloy were systematically studied. Experimental results showed that the high laser power could effectively reduce the influence of fine powders splash on the processability of the samples. The maximum relative density of the sample reached 98.6%. The microstructures of the samples composed of fine equiaxed grains and coarse grains. The increase of Mg content in Al-Mg-Sc-Zr alloy reduced the texture and the content of columnar grains. The micro-hardness first increased and then decreased with the increases of aging temperatures. Both micro-hardness and compression yield strength showed dual-peak phenomenon with the increase of aging time at 350 ℃. The maximum micro-hardness ~ 163±3 HV and compressive yield strength ~ 457±10 MPa appeared for the sample ageing treatment at 350 ℃ for 1 h, with an elongation of 27±3%. After aged the samples at 350 ℃ for a long time, the micro-hardness and compressive yield strength of the sample decreased due to coarsening of the precipitated particles. In this study, the utilization ratio of the powders were efectively improved by increasing the particle size distribution of alloy powders, and SLM-formed high Mg-content Al-Mg-Sc-Zr alloy exhibited good processability and mechanical properties.