基于增材制造的原位合金化制造方法的研究进展

Research Progress of In Situ Alloying Manufacturing Method Based on Additive Manufacturing

基于增材制造的原位合金化方法是利用激光或电子束将多种元素粉或多种预合金粉的混合粉末熔化,使材料同时进行合金化和致密化的一种成本低廉、快速高效的开发新材料的方法,已经在高熵合金开发、新型生物医用合金打印件开发等领域得到初步应用。总结了混合粉末的形貌、粒径、高熔点粉末含量及粉末混合技术对原位合金化打印件性能的影响的研究结果。研究表明,混合粉末的颗粒级配需要同时保证元素混合均匀性和粉末流动性,才能保证原位合金化打印效果。激光功率、束斑直径、重熔工艺等打印参数对熔池几何特征影响很大,继而也强烈影响原位合金化的效果。熔池深度越大,越能保证打印过程中的层间重熔,促进元素均匀,但过深的熔池会造成孔隙。还介绍了基于原位合金化打印制备具有成分波动或成分梯度的合金材料的研究进展。原位合金化工艺本身固有的成分不均匀性有助于制备成分不均匀的合金,从而获得具有双相结构的打印件,这是基于预合金粉打印无法得到的。基于多材料及多相流模型,原位合金化粉床激光熔融过程的数值模型也被研究者建立,模拟得出的原位合金化的增材制造工艺优化参数与针对预合金粉打印的差别很大。最后对增材制造原位合金化技术的应用前景和面临的挑战作出了展望。

In situ alloying based on additive manufacturing of blends of several kinds of elemental or alloyed powders is a low cost,rapid and efficient method to develop new materials,which has been preliminarily applied in the fields of high en-tropy alloy development,new biomedical alloy printing development and so on.In this paper,the effects of powder morphol-ogy,particle size,high melting point powder content,powder mixing technology on the performance of in situ alloying prin-ted samples are introduced.The results show that in order to ensure the in situ alloying printing effect,the particle gradation of mixed powder should ensure both the element mixing uniformity and the powder fluidity.The printing technology including laser power,beam spot diameter and remelting strategy also influences the geometry of the melting pools,which in turn,af-fect the in situ alloying process.The greater the pool depth,the more guarantee the interlayer remelting in the printing process,promote the element uniformity,but too deep pool will cause pores.The study of alloys with composition fluctuation or gradient based on in situ alloying printing is also introduced.It has been shown that the inhomogeneity of composition which is inherent in the in situ alloying process facilitates the preparation of alloys with inhomogeneous com-position,resulting in bi-phasic additive printing,which cannot be obtained by printing based on pre-alloy powders.Based on the multi material and multiphase flow model,the numerical model of laser melting process of in situ alloying has also been established.The numerical simulation of laser pow-der bed fusion based on in situ alloying shown that the optimized in situ alloying process was different from that of laser pow-der bed fusion based on pre-alloyed powder.Finally,the application prospect and challenges of in situ alloying technology based on additive manufacturing are prospected.