粉末增材制造微结构的非等温相场模拟  

Non-isothermal phase-field simulation of microstructure in powder-based additive manufacturing

作　　者：杨阳祎玮 易敏 胥柏香 YANG Yangyiwei;YI Min;XU Baixiang(Department of Materials and Earth Sciences,Technical University of Darmstadt,Darmstadt D-64287,Germany;College of Aerospace,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China;State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]达姆施塔特工业大学材料与地质科学系,德国达姆施塔特D-64287 [2]南京航空航天大学航空学院,江苏南京210016 [3]南京航空航天大学机械结构力学及控制国家重点实验室,江苏南京210016

出　　处：《中南大学学报（自然科学版）》2020年第11期3019-3031,共13页Journal of Central South University:Science and Technology

基　　金：德国科学基金资助项目(CRC-TRR 270,DFG YI 165/1-1,DFG XU 121/7-1);国家海外高层次人才引进计划青年项目(2018);机械结构力学及控制国家重点实验室资助项目(MCMS-I-0419G01)。

摘　　要：为了预测粉末增材制造过程中微结构特点及其演化过程,考虑增材制造中局部温度的剧烈变化和极大的温度梯度,改进热-熔体-微结构耦合的非等温相场模型。在该相场模型中,微结构演化由传质、传热、熔体流动、固液相变和晶体生长的耦合动力学所描述。采用有限元方法对该模型进行数值求解,并将其应用于粉末的非等温烧结以及选区烧结(selective sintering,SS)和选区熔化(selective melting,SM)增材制造的模拟。研究结果表明:温度梯度将产生额外的热毛细和热泳传质,以及固/液界面移动和晶界迁移的额外驱动力,进而显著影响微结构演化;该模型可预测高能集中热束功率P和扫描速度v对孔隙率、表面形貌、温度分布、晶粒形状及取向、致密度等微观结构特征的影响规律;当P-0.15v-23>0(SS)和P-0.25v-100>0(SM)时,可获得大于90%的致密度。In order to predict the microstructure and its evolution during the powder-based additive manufacturing(AM) and consider the drastic change in local temperature and thus the extremely high temperature gradient therein, a non-isothermal phase-field model with the coupled heat-melting-microstructure process was developed.In this model, the microstructure evolution was described by the coupled kinetics of mass transfer, heat transfer,melting flow, solid-liquid phase transition and grain growth. The model was numerically implemented by finite element method, and further applied to the phase-field simulation of non-isothermal sintering and selective sintering(SS)/selective melting(SM) based AM of powder. The results show that the temperature gradient generates the additional diffusive and thermophoresis mass transfer, as well as the additional driven force for solid/liquid interface movement and grain boundary migration, thus notably influencing the microstructure evolution.The model is demonstrated to be capable of predicting the effects of beam power P and scanning speed v on the SS/SM AM induced microstructure features such as porosity, morphology, temperature distribution, grain shape/orientation, denitrification, etc. In the case of P-0.15 v-23>0 for SS and P-0.25 v-100>0 for SM, the microstructure with a denitrification factor above 90% can be obtained.

关 键 词：粉末增材制造 相场模型 微结构 选区烧结/熔化 温度梯度 有限元方法 

分 类 号：TH166[机械工程—机械制造及自动化]