时效处理温度对一种第四代镍基单晶高温合金组织与持久性能的影响-中国材料进展

文章信息/Info

Title:: The Effect of Aging Treatment Temperature on Microstructure and Stress-Rupture Properties of a Fourth Generation Ni-Based Single Crystal Superalloy

Author(s):: LI Yuan; ZHAO Yunsong; GUO Yuanyuan; ZHANG Jian; YANG Zhenyu; ZHENG Shuai; LIU Chenguang; TANG Dingzhong; Science and Technology on Advanced High Temperature Structural Materials laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095, China

Keywords:: Ni-based single crystal superalloy; aging treatment; microstructure; high temperature stress-rupture property; fracture morphology

摘要:: 为探究一次时效温度对一种第四代镍基单晶高温合金显微组织和高温持久性能的影响，使用高分辨率场发射扫描电镜和金相显微镜对合金热处理前后显微组织、高温持久断口形貌和断后剖面显微组织进行观察。结果表明：固溶处理可以使（γ+γ′）共晶组织基本消除，合金元素的偏析程度明显减轻。一次时效处理改变γ′相尺寸与形貌，一次时效温度升高使枝晶干γ′相尺寸增加、立方度降低，γ基体通道宽度增加。随着一次时效温度升高，合金在1120 ℃/137 MPa条件下的持久寿命降低。合金持久性能与γ′相形貌尺寸、体积分数及γ基体通道宽度密切相关。尺寸合适且立方度高的γ′相对位错有较强阻碍作用，且位错在γ基体通道内滑移所需的Orowan应力与基体通道宽度呈反比。通过综合对比评估，确定了该合金最佳一次时效温度为1140 ℃。

Abstract:: To investigate the influence of primary aging temperature on the microstructure and stress-rupture properties of a fourth-generation Ni-based single-crystal superalloy, high-resolution field emission scanning electron microscopy and optical microscopy were employed to characterize microstructural evolution during heat treatment, high-temperature stressrupture fracture morphology and microstructure of cross-sections. The results revealed that solution treatment effectively eliminated (γ+γ′) eutectic structures and substantially reduced elemental segregation. Primary aging modified γ′ precipitate size and morphology, where increasing temperature promoted γ′ coarsening in dendritic areas, diminished cuboidal integrity and widened γ matrix channels. Consequently, elevated primary aging temperatures reduced the stress-rupture life at 1120 ℃/137 MPa. The stressrupture performance exhibited critical dependence on γ′ precipitate morphology, size, volume fraction and γ channel width. Optimally sized, highly cuboidal γ′ precipitates strongly impeded dislocation motion, while the Orowan stress for dislocation glide within γ channels demonstrated inverse proportionality to channel width. Comprehensive evaluation established 1140 ℃ as the optimal primary aging temperature for this alloy.