选区激光熔化成型铝合金的研究现状及展望

Research Status and Prospect of Aluminum Alloy Manufactured by Selective Laser Melting

随着航空航天、汽车轻量化的需求不断上升,经过结构优化的复杂金属构件采用增材制造技术一体成型必然是今后高端产品制造业的发展趋势。铝合金优异的综合性能与远低于钛合金原料的价格,使其在增材制造领域中极具应用和研究潜力。金属增材制造方法繁多,选区激光熔化技术(SLM)由于成型件表面质量优良、综合性能优异,在复杂结构与薄壁结构集成化的零件成型中具有显著优势,颇受科研和工业界关注。然而,由于铝合金粉末具有激光反射率高、热导率较大、流动性较差且易与氧气发生反应等特点,使得成型件极易产生球化、裂纹、孔隙、氧化夹杂等冶金缺陷,不能满足实际应用中的性能要求。其中,研究较为深入的AlSi10Mg、Al-12Si等铸造系铝合金并不能满足很多领域对强度的要求,高强合金在SLM成型过程中极易发生元素烧损、产生裂纹等不良现象。因此,明确各类缺陷的形成机理辅助调控SLM成型铝合金的工艺参数以减少缺陷产生,开发适用于SLM成型的新型铝合金粉末成为学者们的研究焦点。本文主要从Al-Si系铸造合金、高强铝合金以及铝基复合材料三个方面来介绍近年来SLM成型铝合金的研究进展。针对SLM成型的铝合金种类少、成型工艺条件不成熟、冶金缺陷难以控制以及零件性能与微观组织间的量化研究不系统的困境,提出可以引入材料基因工程(MGE)的理念,结合人工智能技术寻求成分-组织-工艺-性能之间的量化关系,开发适用于SLM成型特点的新型铝合金粉末,实现从应用需求出发反向设计材料成分与工艺的目的。

With the increasing demand for lightweighting in aerospace and automobiles,the integration of structurally optimized complex metal components with additive manufacturing technology is bound to be the future development trend of the high-end product manufacturing industry.The excellent comprehensive performance of aluminum alloy and the far lower price than titanium alloy make it have great application and research potential in additive manufacturing.There are many methods of metal additive manufacturing.Selective laser melting(SLM)has attracted the attention of scientific research and industry because of its excellent surface quality and comprehensive performance,which has significant advantages in the forming of parts with complex structures and thin-walled structure integration.However,due to the characteristics of high laser reflectivity,high thermal conductivity,poor fluidity and easy reaction with oxygen,the molded parts are prone to metallurgical defects such as balling,cracks,pores and oxidation inclusions,which cannot meet the performance requirements in practical applications.AlSi10Mg,Al-12Si and other cast aluminum alloys studied deeply can not meet the strength in many fields.High-strength alloys are extremely prone to undesirable phenomena such as element burning and cracking during SLM forming.Therefore,it has become the research focus to develop a series of new aluminum alloy powders and clarify the formation mechanism of various defects to reduce the generation of defects during the SLM process.In this paper,the researchstatus of aluminum alloy by SLM in recent years has been introduced from three aspects:Al-Si casting alloy,high strength aluminum alloy,and aluminum matrix composite.In view of the dilemma of aluminum alloys formed by SLM,such as the parameters of process conditions are immature,the metallurgical defects are difficult to control,and the quantitative research between part performance and microstructure is not systematic.The author proposes that the concept of material genetic engineering(MGE)can be introduced and combined with artificial intelligence technology to seek a quantitative relationship between composition-microstructure-process-performance.It is helpful to develop a new type of aluminum alloy powder suitable for SLM characteristics,and achieve the purpose of reverse design of material composition and process from the application requirements.