致密化及显微组织
(1. 南京航空航天大学 材料科学与技术学院，南京 210016；
2. Fraunhofer Institute for Laser Technology ILT, Aachen D-52074, Germany)
摘 要: 利用选区激光熔化(SLM)工艺制备TiCx增强Ti基纳米复合材料试件；通过X射线衍射仪和场发射扫描电子显微镜等研究激光线能量密度η(激光功率与扫描速率之比)对选区激光熔化试件的致密化过程、物相及显微组织的影响规律，并讨论激光快速熔凝过程中TiC0.625层片状纳米结构的形成机理。结果表明：当激光线能量密度η为1 100 J/m时，成形试件的致密度可达95.6%；其内部增强体为层片状纳米结构，平均厚度为54 nm，且在Ti基体中分布均匀。增强相TiCx以亚化学计量TiC0.625形式存在，具有立方晶体结构。
关键字: 选区激光熔化；线能量密度；致密度；显微组织；TiC0.625
中图分类号：TG146.2 文献标志码：A
TiCx/Ti nanocomposites prepared by selective laser melting
（1. College of Materials Science and Technology,
Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
2. Fraunhofer Institute for Laser Technology ILT, Aachen D-52074, Germany）
Abstract:The TiCx reinforced Ti matrix nanocomposites parts were prepared by selective laser melting (SLM). The effects of applied linear laser energy density η (the ratio of laser power to scan speed) on evolutions of the densification behavior, phases, and microstructures of SLM-processed parts were studied using X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM). The formation mechanism of TiC0.625 reinforcing phase with a lamellar nanostructure during the laser-induced rapid melting/solidification process was discussed. The results show that a high densification level of 95.6% is obtained for SLM-processed parts at a laser linear energy density η of 1 100 J/m. The TiCx reinforcing phase disperses uniformly in the Ti matrix, having an ultrafine lamellar nanostructure with an average thickness of 54 nm. The reinforcing phase is present in the form of substoichiometric TiC0.625 with a cubic crystal structure.
Key words: selective laser melting (SLM); linear energy density; densification; microstructure; TiC0.625
