Effects of Heat Treatment on Microstructure and Mechanics Properties of GH5188 Co-based Alloys Fabricated by Laser Directed Energy Deposition

doi:10.3969/j.issn.1004-132X.2026.06.004

Abstract

Abstract:

GH5188 alloys were fabricated by LDED， and different heat treatments were subsequently applied to enhance the mechanics performance of LDED-fabricated （LDEDed） samples. The LDEDed GH5188 alloys exhibited a predominantly coarse columnar grain structure， with γ-Co matrix and M₂₃C₆ eutectic carbides distributed at the grain boundaries. The solution treatment promoted the segregation of solute elements， which acted as new nucleation sites and facilitated recrystallization as well as grain refinement. In addition， the initially coarse and irregular γ-Co/M₂₃C₆eutectic phases enriched at grain boundaries were refined into finely dispersed particle-like precipitates， thereby strengthening the precipitation hardening effects. An excellent strength-ductility balance of LDEDed GH5188 alloys with an ultimate tensile strength of 857 MPa and an elongation of 42% is attained after solution treatment（1180 °C-1 h）. These results demonstrate that solution treatment effectively alleviates the coarse grain structure and uneven distribution of precipitates inherent to the LDEDed GH5188 alloys， thereby enhancing the overall mechanics performances.

Key words: laser directed energy deposition（LDED）, GH5188 co-based alloy, solution treatment, microstructure, mechanics property

摘要：

采用激光定向能量沉积（LDED）工艺制备了GH5188合金，研究了不同固溶处理温度对沉积层微观组织及力学性能的影响规律。结果表明，沉积态组织主要呈现外延生长的粗大柱状晶，基体为γ-Co相，晶界处富集M₂₃C₆共晶碳化物；固溶处理促进了溶质元素的偏聚，为再结晶提供了额外的形核位点，从而加速了再结晶过程并实现了晶粒细化；同时，沿晶界分布的粗大不规则γ-Co/M₂₃C₆共晶相被细化为弥散分布的颗粒状析出相，有效增强了沉淀强化效应。经1180 ℃保温1 h处理后，LDED成形GH5188合金获得了良好的强塑性匹配，极限抗拉强度和延伸率分别达到了857 MPa和42%。固溶处理能够有效改善沉积态组织中晶粒粗大及析出相分布不均的问题，从而提高LDED成形GH5188合金的力学性能。

关键词: 激光定向能量沉积, GH5188钴基合金, 固溶处理, 微观组织, 力学性能

CLC Number:

TH164

LU Haifei, WANG Zhenyu, LUO Kaiyu, LU Jinzhong. Effects of Heat Treatment on Microstructure and Mechanics Properties of GH5188 Co-based Alloys Fabricated by Laser Directed Energy Deposition[J]. China Mechanical Engineering, 2026, 37(6): 1305-1317.

卢海飞, 王振宇, 罗开玉, 鲁金忠. 热处理对激光定向能量沉积GH5188钴基合金微观组织与力学性能的影响[J]. 中国机械工程, 2026, 37(6): 1305-1317.

Figures/Tables 14

Fig.1 Process flow diagram of LDED GH5188 alloy

Fig.2 OM images of single tracks fabricated with different laser powers and scanning speeds

Fig.3 XRD patterns of all samples

Fig.4 OM photographs of as-built sample

Fig.5 EBSD analyse results

Fig.6 EBSD results of grain boundary maps

Fig.7 EBSD results of KAM

Fig.8 SEM photographs

Fig.9 TEM images and EDS mapping

Fig.10 Typical TEM micrographs

Fig.11 Microhardness evolution of all samples

Fig.12 Tensile engineering stress-strain curves， and Comparison of the corresponding YS， UTS and EL

Fig.13 Tensile fracture morphology of all samples

Fig.14 Schematic illustration of the microstructural evolution mechanism of the GH5188 alloy fabricated by LDED during solution treatment at 1180 ℃

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