Ni-Al-Re三元模型单晶高温合金γ/γ′相界面应变场

Strain Field at the γ/γ′ Phase Interface in Ni-Al-Re Ternary Model Single-Crystal Superalloys

摘要: 镍基单晶高温合金对我国航空航天事业发展至关重要，是高端动力装备和高温部件不可替代的核心材料，γ/γ′相界面晶格应变场是决定其组织稳定性与服役性能的重要因素。难熔元素Re是先进镍基单晶高温合金的核心强化元素。本文以Ni-Al-Re三元模型单晶高温合金为研究对象，采用会聚束电子衍射(CBED)，系统表征了合金两相晶格常数及界面错配度，枝晶干两相错配度为0.25%，枝晶间两相错配度为0.28%，同时，Re削弱了合金长程应变场，缩短γ′相应变影响范围、降低其宏观压应变，且应变场存在显著枝晶差异性，为高性能镍基单晶高温合金的成分优化提供了关键数据支撑。

Abstract: Nickel-based single-crystal superalloys are of vital importance to the development of aerospace industry in China, serving as irreplaceable core materials for high-end power equipment and high-temperature components. The lattice strain field at the γ/γ′ phase interface is a key factor governing the microstructural stability and service performance of such alloys. The refractory element rhenium (Re) acts as the primary strengthening element in advanced nickel-based single-crystal superalloys. In this paper, a Ni-Al-Re ternary single-crystal superalloy is taken as the research object. Convergent beam electron diffraction (CBED) is employed to systematically characterize the lattice parameters of the two phases and the interfacial misfit in the alloy. The two-phase misfit is measured to be 0.25% in the dendrite core and 0.28% in the interdendritic region. Re weakens the long-range strain field of the alloy, shortens the strain influence range of the γ′ phase, and reduces its macroscopic compressive strain; meanwhile, the strain field exhibits obvious dendrite-dependent heterogeneity. Providing critical data support for the compositional optimization of high-performance nickel-based single-crystal superalloys.