杨海欧,赵宇凡,许建军,等.激光立体成形Rene88DT镍基高温合金沉积态组织研究[J].精密成形工程,2019,11(4):9-14.
YANG Hai-ou,ZHAO Yu-fan,XU Jian-jun,et al.AS-Deposited Microstructures of Rene88DT Nickel-base Superalloy by Laser Solid Forming[J].Journal of Netshape Forming Engineering,2019,11(4):9-14. |
| 激光立体成形Rene88DT镍基高温合金沉积态组织研究 |
| AS-Deposited Microstructures of Rene88DT Nickel-base Superalloy by Laser Solid Forming |
| 投稿时间：2019-06-28 修订日期：2019-07-10 |
| DOI：10.3969/j.issn.1674-6457.2019.04.002 |
| 中文关键词: 激光立体成形（LSF） 增材制造 Rene88DT合金 组织 相组成 |
| 英文关键词: laser solid forming (LSF) additive manufacturing Rene88DT alloy microstructure phases constitution |
| 基金项目:国家重点研发计划（2018YFB1105804）；民用飞机专项科研（MJ-2017-G-63） |
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| 中文摘要: |
| 目的 基于激光立体成形（Laser Solid Forming, LSF）过程中所存在的近快速凝固特性，以Rene88DT合金为研究对象，考察激光立体成形Rene88DT沉积态微观组织特征和相形成规律。方法 通过LSF技术制备Rene88DT镍基高温合金单道沉积试样，采用光学显微镜（OM）和扫描电子显微镜（SEM）对组织进行观察，并用能谱仪（EDS）对试样中的析出相及微区成分进行分析。结果 激光立体成形Rene88DT合金沉积态组织主要由沿趋于平行沉积方向生长的γ柱状晶组成，由于枝晶偏析的存在，以富Nb为主的块状MC碳化物以及板条状η（Ni3Ti）相于枝晶间区域析出。随着沉积高度的增加，一次枝晶臂间距有所增大，二次枝晶臂逐渐发达，同时，γ'相体积分数和尺寸逐渐减小，沉积层的硬度相应降低。结论 尽管激光立体成形熔池凝固已属于近快速凝固范围，熔池凝固过程中，溶质原子同样易于在晶界处形成偏聚，导致晶界弱化，在成形热应力作用下易形成沿晶裂纹。 |
| 英文摘要: |
| Based on the near-fast solidification characteristics in laser solid forming (LSF), this paper aims to investigate the characteristic of microstructures and phase constitution of as-deposited Rene88DT alloy by LSF. As-deposited Rene88DT nickel-base superalloy samples were fabricated by LSF; their microstructures were observed with optical microscope (OM) and scanning electron microscope (SEM); and the precipitated phase and micro-region composition in the specimen were analyzed with energy spectrometer (EDS). It was found that the as-deposited microstructure mainly consisted of predominant γ columnar dendrites epitaxially growing along the deposition direction. The existence of the micro-segregation made the block MC carbide that was mainly rich in Nb and lath-shaped η (Ni3Ti) phase precipitated from the interdendritic regions. With the increase of the height of samples made by LSF, the primary dendrite arm spacing (λ1) increased to some extent, and the secondary arms were gradually developed. The volume fraction and size of phase γ' decreased gradually and the hardness of the deposited layer decreased accordingly. Although LSF melt pool solidification has been in the near-fast solidification range, the segregation of solute atoms at grain boundaries during LSF might led to grain-boundary weakness. Therefore, the intergranular crack can form in the presence of thermal stress in LSF. |
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