致密化及顯微組織
(1. 南京航空航天大學 材料科學與技術(shù)學院，南京 210016；
2. Fraunhofer Institute for Laser Technology ILT, Aachen D-52074, Germany)
摘 要: 利用選區(qū)激光熔化(SLM)工藝制備TiCx增強Ti基納米復合材料試件；通過X射線衍射儀和場發(fā)射掃描電子顯微鏡等研究激光線能量密度η(激光功率與掃描速率之比)對選區(qū)激光熔化試件的致密化過程、物相及顯微組織的影響規(guī)律，并討論激光快速熔凝過程中TiC0.625層片狀納米結(jié)構(gòu)的形成機理。結(jié)果表明：當激光線能量密度η為1 100 J/m時，成形試件的致密度可達95.6%；其內(nèi)部增強體為層片狀納米結(jié)構(gòu)，平均厚度為54 nm，且在Ti基體中分布均勻。增強相TiCx以亞化學計量TiC0.625形式存在，具有立方晶體結(jié)構(gòu)。
關(guān)鍵字: 選區(qū)激光熔化；線能量密度；致密度；顯微組織；TiC0.625
中圖分類號：TG146.2 文獻標志碼：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
