Lyu Feiyue, Liu Fencheng, Hu Xiaoan, Yang Xiaoguang, Huang Chunping, Shi Duoqi
School of Aeronautical Manufacturing and Engineering, Nanchang Hangkong University, Nanchang 330063, China.
School of Aircraft Engineering, Nanchang Hangkong University, Nanchang 330063, China.
Materials (Basel). 2019 Aug 15;12(16):2604. doi: 10.3390/ma12162604.
Fabricating an Inconel 718 superalloy using electromagnetic stirring assisted laser solid forming (EMS-LSF) is a novel method to modify its microstructure and mechanical properties by consuming the Nb element in the γ phase to alleviate interdendritic segregation. The precipitate of the δ phase at 950 °C after EMS-LSF can help to achieve the uniform diffusion of Nb, and can also improve its mechanical properties. The precipitation behavior of the δ phase in an EMS-LSF Inconel 718 superalloy with different heat treatment processes has been investigated. The results show that the morphology of the δ phase changes from rod-like to a long-needle shape and tends to grow from the inter dendrite to the core dendrite with electromagnetic field intensity increasing, which is accompanied by the "cutting" and "dissolution" of the Laves phase. Through precipitation kinetics analysis, the precipitation rate of the δ phase is seen to increase with the electromagnetic field intensity increasing. Under a combination of electromagnetic stirring and laser solid forming, the microhardness of the Inconel 718 samples increased slightly due to the fact that a higher content of Nb was distributed in the core dendrite resulting from the serious convection of liquid metal, which can strengthen the matrix.
利用电磁搅拌辅助激光立体成形（EMS-LSF）制备Inconel 718高温合金是一种通过消耗γ相中的铌元素来减轻枝晶间偏析，从而改善其微观结构和力学性能的新方法。EMS-LSF后在950℃下δ相的析出有助于实现铌的均匀扩散，还能改善其力学性能。研究了不同热处理工艺的EMS-LSF Inconel 718高温合金中δ相的析出行为。结果表明，随着电磁场强度的增加，δ相的形态从棒状变为长针状，并倾向于从枝晶间向枝晶核心生长，同时伴随着Laves相的“切割”和“溶解”。通过析出动力学分析可知，δ相的析出速率随电磁场强度的增加而增大。在电磁搅拌和激光立体成形的共同作用下，Inconel 718试样的显微硬度略有增加，这是因为液态金属的强烈对流使较高含量的铌分布在枝晶核心，从而强化了基体。
