Effects of substrate crystallographic orientations on crystal growth and microstructure formation in laser powder deposition of nickel-based superalloy
Effects of substrate crystallographic orientations on crystal growth and microstructure formation in laser powder deposition of nickel-based superalloy
复制标题
基体晶体取向对镍基高温合金激光粉末沉积晶体生长和微观结构形成的影响
DOI：
10.1016/j.actamat.2014.12.046
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发表时间：
2015-04-01
期刊：
影响因子：
9.4
通讯作者：
Qi, Huan
中科院分区：
文献类型：
--
作者：
Liu, Zhaoyang;Qi, Huan
建立了镍基高温合金激光粉末沉积的三维数学模型。采用数学模型和实验方法研究了不同取向基底上沉积珠粒的晶体生长和微观结构的形成。用单晶镍基高温合金Rene N5进行了LPD实验，验证了计算结果。结果表明：熔池纵断面衬底晶体取向的变化主要影响柱状枝晶向等轴转变的位置，而横断面衬底晶体取向的变化主要影响柱状枝晶择优生长方向的竞争以及相应的微观结构的形成。在纵向截面上，随着衬底晶体取向的倾角α从-30°变化到+30°，外延晶体的高度比从9°增加到94%，几乎呈线性增长。在横截面上，当衬底晶体的倾角β从0°变化到+45°时，柱状枝晶的首选外延生长方向的过渡线出现，并从熔池边缘向中心轴线偏移。模拟结果与实验观察到的晶体生长方向及其在沉积中的分布吻合较好。(C) 2015材料学报Elsevier Ltd.出版。版权所有。
A three-dimensional mathematical model was developed for the laser powder deposition (LPD) of nickel-based superalloy. The crystal growth and microstructure formation in the deposited bead on substrates with various crystallographic orientations were studied through mathematical modeling and experimental approaches. LPD experiments with single-crystal nickel-based superalloy Rene N5 were performed to verify the computational results. The results show that the variation of substrate crystallographic orientation in the longitudinal section of the molten pool mainly influences the position of columnar to equiaxed transition, whereas in the transverse section it mainly influences the competitiveness of the preferred growth direction of columnar dendrites and the corresponding microstructure formation. In the longitudinal section, the height ratio of the epitaxial crystal shows an almost linear increase from 9 to 94% as the inclination angle alpha of the substrate crystallographic orientation changes from -30 to +30 degrees. In the transverse section, when the inclination angle beta of the substrate crystalline changes from 0 to +45 degrees, the transition line of the preferred epitaxial growth direction of columnar dendrites appears and shifts from the edge to the center axis of the molten pool. The simulation results agree well with the experimentally observed crystal growth directions and their distributions in the deposition. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.