Directed energy deposition (DED) of Inconel 718 is a promising process for the reconstruction of aerospace components, but a large number of Laves phases precipitated in inter-dendrites can impair the mechanical properties of the reconstructed parts. This paper puts forward a gradient laser power (GLP) deposition method to tailor the morphology and content of the Laves phase effectively, thereby enhancing the mechanical properties. The deposited Inconel 718 parts with the same volume as the Inconel 718 substrate were fabricated by different laser powers to simulate the practical thin-wall repair. An infrared camera was utilized to capture the thermal information during the DED process. The thermal-history-dependent microstructure, residual stress, microhardness and tensile properties were comprehensively investigated. The results indicate that the GLP method not only alleviates heat accumulation but also increases cooling rates and lateral heat dissipation. For GLP samples, the discrete and fine Laves phases tailored with a uniform distribution are featured by fine columnar dendrites with random growth direction, in sharp contrast to their long-chain interconnected configurations obtained by the conventional constant laser power (CLP) deposition method. Compared with CLP samples, GLP samples show compressive residual stress, high hardness and excellent ductility of elongation 30.09 % with comparable strength.

Inconel 718 的定向能量沉积 (DED) 是一种很有前景的航空航天部件重建工艺，但在枝晶间析出的大量 Laves 相会损害重建部件的机械性能。本文提出了一种梯度激光功率（GLP）沉积方法，以有效地调整 Laves 相的形貌和含量，从而提高机械性能。沉积的 Inconel 718 零件与 Inconel 718 基板具有相同的体积，通过不同的激光功率制造，以模拟实际的薄壁修复。在 DED 过程中，红外摄像机用于捕获热信息。综合研究了与热历史相关的微观结构、残余应力、显微硬度和拉伸性能。结果表明，GLP 方法不仅减轻了热量积累，而且提高了冷却速度和横向散热。对于 GLP 样品，具有均匀分布的离散和精细 Laves 相的特征是具有随机生长方向的细柱状枝晶，这与通过传统恒定激光功率 (CLP) 沉积方法获得的长链互连配置形成鲜明对比。与 CLP 样品相比，GLP 样品显示出压缩残余应力、高硬度和优异的延展性，伸长率为 30.09%，具有可比的强度。具有均匀分布的离散和精细 Laves 相的特点是具有随机生长方向的精细柱状枝晶，与通过传统恒定激光功率 (CLP) 沉积方法获得的长链互连配置形成鲜明对比。与 CLP 样品相比，GLP 样品显示出压缩残余应力、高硬度和优异的延展性，伸长率为 30.09%，具有可比的强度。具有均匀分布的离散和精细 Laves 相的特点是具有随机生长方向的精细柱状枝晶，与通过传统恒定激光功率 (CLP) 沉积方法获得的长链互连配置形成鲜明对比。与 CLP 样品相比，GLP 样品显示出压缩残余应力、高硬度和优异的延展性，伸长率为 30.09%，具有可比的强度。