Towards extensive comprehension of Stress Assisted Grain Boundary Oxidation in Ni superalloys - strain localization and crack evolution

Ni superalloys are known for their outstanding performance under harsh environments. They can, however, suffer from stress corrosion cracking (SCC) when their applications involve high temperature, oxidative media, and mechanical loading. Stress Assisted Grain Boundary Oxidation (SAGBO) shares the same degradation patterns in a way to mimic such SCC degradation in time scales that are compatible with laboratory experiments. Therefore we propose an experiment to perform an in-situ analysis of SAGBO using 3D bulk characterization techniques. We intend to have initial grain maps obtained by diffraction contrast tomography, a time-lapse of phase contrast tomography volumes to feed digital image correlation routines and compare to the results of strain fields obtained by far-field X ray diffraction techniques.

镍基高温合金（Ni superalloys）以其在严苛环境下的卓越性能而闻名。然而，当其应用场景涉及高温、氧化介质与机械载荷时，这类合金易发生应力腐蚀开裂（Stress Corrosion Cracking，SCC）。应力辅助晶界氧化（Stress Assisted Grain Boundary Oxidation，SAGBO）的降解模式与应力腐蚀开裂的降解模式高度一致，且其发生的时间尺度适配实验室实验条件，可模拟应力腐蚀开裂的降解过程。因此，本研究提出一项实验方案，采用三维体相表征技术对应力辅助晶界氧化进行原位分析。我们计划通过衍射衬度层析成像技术获取初始晶粒图谱，利用相衬层析成像的体数据延时序列为数字图像相关算法提供输入，并将其与远场X射线衍射技术得到的应变场结果进行对比分析。