中国激光, 2019, 46 (11): 1102008, 网络出版: 2019-11-09
激光熔化沉积Ti6Al4V/Inconel625梯度耐高温涂层组织演变行为研究 下载: 911次
Microstructure Evolution Behavior in Laser Melting Deposition of Ti6Al4V/Inconel625 Gradient High-Temperature Resistant Coating
激光技术 激光熔化沉积 梯度耐高温涂层 钛合金 镍基合金 laser technique laser melting deposition gradient high-temperature resistant coating titanium alloy nickel-based alloy
摘要
采用激光熔化沉积技术制备了组织致密,无裂纹、无孔洞等缺陷的Ti6Al4V/Inconel625梯度耐高温涂层,通过扫描电镜、能谱仪、X射线衍射等分析技术对梯度涂层的显微组织、成分及相变进行研究。结果表明:随着成分梯度的变化,涂层的显微组织由片层α和β相组成的片层组织转变为等轴组织,且随着镍基合金含量的增多,合金元素数量增多,液相熔池中的溶质浓度增加,成分过冷明显,形核率增大,组织进一步细化;梯度耐高温涂层的相组成发生了如下变化:α+β→α+β+Ti2Ni→Ti2Ni+β→Ti2Ni+CrNi2+γ-Ni,在晶间区域内存在β-Ti与Ti2Ni离析共晶,此外还存在CrNi2相;随着Inconel625含量增加,梯度涂层的硬度增大,当镍基合金的体积分数为100%时,在共析强化和固溶强化的共同作用下,硬度达到峰值855 HV;梯度涂层的硬度主要与β相、Ti2Ni析出物和CrNi2化合物以及溶质元素的含量有关。
Abstract
Herein, Ti6Al4V/Inconel625 gradient high-temperature resistant coating with dense microstructure, no cracks, holes, and other defects is prepared via laser melting deposition. The microstructure, composition, and phase transformation of the gradient coating are studied via scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Results show the microstructure changes from a lamellar structure comprising lamellar α and β phases to an equiaxed structure with changes in the compositional gradient. Further, as the nickel-based alloy composition increases, the amount of alloying elements and concentration of solute in the liquid molten phase increase. Additionally, when the coating composition is too cold, the nucleation rate increases and the microstructure is further refined. The phase composition of the gradient high-temperature resistant coating changes as follows: α+β → α+β+Ti2Ni → Ti2Ni+β → Ti2Ni+CrNi2+γ-Ni. β-Ti and Ti2Ni exist as isolated eutectic phases in the intergranular region, in the presence of a CrNi2 phase. As the Inconel625 content increases, the hardness of the gradient coating increases. When the volume fraction of the nickel-based alloy reaches 100%, the hardness reaches a peak of 855 HV under the combined action of eutectoid strengthening and solid-solution strengthening. The hardness of the gradient coating is mainly related to the contents of β phase, Ti2Ni precipitates, CrNi2 compounds, and solute elements.
季霄, 孙中刚, 唱丽丽, 常辉, 邢飞. 激光熔化沉积Ti6Al4V/Inconel625梯度耐高温涂层组织演变行为研究[J]. 中国激光, 2019, 46(11): 1102008. Xiao Ji, Zhonggang Sun, Lili Chang, Hui Chang, Fei Xing. Microstructure Evolution Behavior in Laser Melting Deposition of Ti6Al4V/Inconel625 Gradient High-Temperature Resistant Coating[J]. Chinese Journal of Lasers, 2019, 46(11): 1102008.