Strain localization in the Alloy 718 Ni-based superalloy: From room temperature to 650 °C
Strain localization in the Alloy 718 Ni-based superalloy: From room temperature to 650 °C
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DOI：
10.1016/j.actamat.2024.119759
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发表时间：
2024-02
期刊：
影响因子：
9.4
通讯作者：
D. Texier;J. Milanese;Malo Jullien;J. Genée;J. Passieux;Didier Bardel;Eric Andrieu;M. Legros;J. Stinville
中科院分区：
文献类型：
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作者：
D. Texier;J. Milanese;Malo Jullien;J. Genée;J. Passieux;Didier Bardel;Eric Andrieu;M. Legros;J. Stinville
使用高分辨率数字图像相关 (HR-DIC) 技术研究了多晶镍基高温合金（合金 718）在室温至 650°C 范围内与微观结构相关的不可逆变形。在保护气氛下进行间断拉伸测试，以确保散斑图案的稳定性，以跟踪表面分析的运动学场。使用 HR-DIC 在扫描电子显微镜 (SEM) 图像上捕获面内应变定位。对与微观结构特征相关的不同应变局部化事件进行了统计分析，即晶内滑移局部化、平行于并靠近Σ 3-孪晶界的滑移局部化（Σ 3-TB）和晶界滑动（GBS）。合金 718 在室温和 350°C 下表现出滑移局域化。从微塑性开始，强烈的应变局域化就平行于 Σ 3-TB 附近发展。由于邻近晶界的两个晶粒上的滑移局域化，几乎没有发现强烈的滑移刺激晶界滑动事件。在 650° C 时，合金 718 在屈服开始时经历了晶界滑动，而相邻晶粒中没有特定的滑动局部化。在较低温度下，平行于Σ 3-TB 并靠近Σ 3-TB 的应变局部化非常强烈，并且晶内滑移局部化随着宏观变形的增加而加剧。在 650° C 下发现了导致过早损坏的特殊微观结构配置：(i) 晶界处的次表面空化，以及 (ii) 由于 Σ 3-TB 附近的强烈剪切而导致晶界开裂。
Irreversible deformation in relation to the microstructure was investigated for a polycrystalline Ni-based superalloy (Alloy 718) from room temperature to 650° C using high-resolution digital image correlation (HR-DIC) techniques. Interrupted tensile tests were performed under a protective atmosphere to ensure the stability of the speckle pattern to track kinematics fields from surface analyses. In-plane strain localization was captured using HR-DIC on scanning electron microscopy (SEM) images. A statistical analysis of different strain localization events in relation to the microstructural features was conducted, ie, intragranular slip localization, slip localization parallel to and near Σ 3-twin boundaries (Σ 3-TB), and grain boundary sliding (GBS). Alloy 718 exhibited slip localization at room temperature and 350° C. Intense strain localization develops parallel and in the vicinity of Σ 3-TB from the onset of the microplasticity. Few intense slip stimulated-grain boundary sliding events were found due to slip localization on both grains adjacent to the grain boundary. At 650° C, Alloy 718 experienced grain boundary sliding at the onset of the yield without particular slip localization in adjacent grains. At lower temperatures, strain localization parallel to and near Σ 3-TB was intense, and intragranular slip localization intensified with increasing macroscopic deformation. Particular microstructural configurations were found at 650° C leading to premature damage:(i) sub-surface cavitation at grain boundaries, and (ii) grain boundary cracking due to intense shearing near a Σ 3-TB.