(1. 中国工程物理研究院 总体工程研究所，绵阳 621999；
2. 西南科技大学 工程材料与结构冲击振动四川省重点实验室，绵阳 621999)
摘 要: 镍基高温合金广泛应用于制造军事和民用工程领域中的关键热端部件，在服役过程中内部沉淀相容易发生粗化，并导致材料力学性能退化。本文结合有限元模拟和机理分析，研究镍基高温合金材料发生沉淀相粗化之后的硬度变化特性，并探讨相关变化与材料微结构演化的关联。结果表明：合金硬度随沉淀相粗化的发生而显著退化，并呈现出各向异性特征，总体来说，当沉淀相体积分数较低或沉淀相粗化程度不高时，其硬度随加载角度增大而先逐渐增加后又逐渐降低；而对于沉淀相体积分数和沉淀相粗化程度均较高的合金，硬度则随加载角度增大而单调升高，合金硬度的相关变化与沉淀相的形状、大小和分布特性密切相关；材料微结构的改变导致内部位错的形核、增殖和运动特性发生变化，进而影响宏观材料的硬度。
关键字: 镍基高温合金；沉淀相粗化；硬度；退化；各向异性
（1. Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 621999, China;
2. Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province, Southwest University of Science and Technology, Mianyang 621999, China）
Abstract:Ni-base superalloys were widely used in the manufacture of the hot-end components in the military and civil engineering. Coarsening of the precipitation phase usually occurs during the service of this kind of precipitate strengthened alloys, and it will induce degradation for their mechanical properties. By integrating with related finite element method (FEM) simulations and mechanism analysis, the present paper focuses on the effect of precipitation phase coarsening on the hardness of Ni-base superalloys, in which the relationship between the evolution of microstructure in the material and its macroscopic mechanical properties was analyzed in detail. After coarsening of the precipitation phase, the results demonstrate that considerable degradation occurs for the hardness of alloys, and the hardness also displays an anisotropic characteristic. In general, when the volume fraction or the coarsening''''s degree of precipitation phase are relatively low, the hardness of alloys increases first and then decreases gradually along with the increase of loading direction. Comparatively, in the case of high volume fraction and high coarsening''''s degree of precipitation phase, the hardness increases monotonously with the loading direction. The related variations of alloy hardness are correlated with the evolution of precipitation phase shape, size and distribution within the alloy. The microstructural evolution changes the manners of the nucleation, multiplication and movement of dislocations within the material, and it further leads to different macroscopic hardness.
Key words: Ni-base superalloy; coarsening of precipitation phase; hardness; degradation; anisotropy
