Mapping stress heterogeneity in single-crystal superalloys by novel submicron-resolved X-ray diffraction

• Published in: Materials research letters 2024-06, Vol.12 (6), p.450-458
• Main Authors: Kou, Jiawei, Chen, Kai, Huang, Shaoqi, Zhai, Chongpu, Chiang, Ching-Yu, Wang, Sisheng, Li, Zhijun, Wang, Yan-Dong
• Format: Article
• Language: English
• Subjects: Coherence; Energy; Finite element analysis; Finite element method; Genomes; Heterogeneity; Laboratories; Lattice parameters; Ni-based single crystal superalloys; Nickel base alloys; nonuniform coherent precipitation; Nonuniformity; Precipitation hardening alloys; Radiation; Single crystals; Strain; Stress distribution; Stress heterogeneity mapping; Stress measurement; submicron-resolved X-ray diffraction; Superalloys; Synchrotron radiation; X-ray diffraction
• ISSN: 2166-3831; 2166-3831
• DOI: 10.1080/21663831.2024.2341932

Coherent precipitation, a common strengthening approach, is typically subjected to spatial non-uniformity due to microscopic segregation, leading to multi-scale stress heterogeneity. Such heterogeneity remains poorly characterized because unavailable local strain-free lattice parameters invalidate traditional diffraction-based stress measurement techniques. To overcome these limitations, we demonstrate a submicron-resolved synchrotron X-ray diffraction method to map coherency stress distribution based on the γ/γ′ lattice misfits in Ni-based superalloys. Assisted by finite element analysis, sub-dendritic stresses are deduced from heterogeneous coherency stresses, confirmed by the diffraction experiments. The methodology offers a comprehensive framework to assess stress heterogeneity at multi-scales for all coherent precipitation strengthened alloys.Impact statementThis study marks the first successful quantification of stress heterogeneity at multi-scales in alloys strengthened by non-uniform coherent precipitation, even in absence of strain-free lattice constants.