激光立体成形石墨烯增强Inconel 625合金增强体分解行为对强韧化的作用机理及调控

激光立体成形Inconel 625合金中连续分布的链状Laves相严重降低了力学性能，调整工艺参数和后热处理对力学性能改善作用有限。添加少量石墨烯并控制工艺参数，使石墨烯部分分解以游离碳原子形式进入合金，可以消耗Laves相的主要形成元素Nb，抑制链状Laves相形成，起到改善合金韧性的作用，而残留石墨烯可以作为增强相提高合金强度，有望实现合金强韧化的目的。本项目通过对成形过程中石墨烯分解行为与分布规律的研究，明晰游离碳原子和残留石墨烯对凝固显微组织的作用机理，并结合热力学和动力学分析，厘清激光立体成形石墨烯增强Inconel 625合金的固态相变行为，建立热处理工艺-显微组织选择图谱，明确游离碳原子和残留石墨烯对合金强度和塑性的影响规律，揭示石墨烯增强Inconel 625合金的强韧化机理。本项目可为实现激光立体成形石墨烯增强金属基复合材料组织和性能主动调控奠定理论基础。

The continuous distribution of chain-like Laves phase seriously reduces the mechanical properties in Inconel 625 superalloy prepared by laser solid forming (LSF). Adjusting process parameters and post heat treatments have limited effect on improvement the mechanical properties. Add a small amount of graphene to Inconel 625 and reasonably control the process parameters to make the graphene partially decompose. After graphene is decomposed, it enters the alloy in the form of carbon atoms. As the carbon content increases in molten pool, the main element Nb of the Laves phase will be consumed. As a result, the formation of chain Laves phase will be inhibited, and the toughness of Inconel 625 will be improved. Additionally, the graphene that has not been decomposed is used as a reinforcing phase to increase the strength of Inconel 625. Therefore, the addition of graphene is expected to achieve the purpose of strengthening and toughening. In this project, through the study of the decomposition behavior and distribution of graphene during the LSF process. The mechanism of carbon atoms and residual graphene on the solidification microstructure is clarified. Combined with thermodynamic and kinetic analysis, to clarify the solid-state phase transformation behavior of graphene reinforced Inconel 625 fabricated by LSF. And the heat treatment process-microstructure selection map is established. The influence of carbon atoms and residual graphene on the strength and plasticity is clarified. The strengthening and toughening mechanisms of graphene-enhanced Inconel 625 is revealed. The research results will lay a theoretical foundation for the realization of active control of the structure and properties of the graphene-enhanced metal matrix composites by LSF.