<p>Local strain and misfit-induced internal stress at the <InlineEquation ID="IEq5"> <EquationSource Format="TEX">$\upgamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">γ</mi> </math></EquationSource> </InlineEquation>/<InlineEquation ID="IEq6"> <EquationSource Format="TEX">$\upgamma ^{\prime }$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi mathvariant="normal">γ</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation> interface of Ni-based single-crystal superalloys play a critical role in dislocation evolution, creep performance, and recrystallization behavior. Although microsegregation at the interface and macroscopic residual stress can be characterized with high precision, a direct and quantitative correlation between local elemental segregation and nanoscale lattice strain at the <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$\upgamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">γ</mi> </math></EquationSource> </InlineEquation>/<InlineEquation ID="IEq8"> <EquationSource Format="TEX">$\upgamma ^{\prime }$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi mathvariant="normal">γ</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation> interface remains insufficiently understood. In this paper, scanning transmission electron microscopy combined with subset geometric phase analysis was used to investigate the microsegregation, interface widths, and full-field strains of interface transition regions with different <InlineEquation ID="IEq9"> <EquationSource Format="TEX">$\upgamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">γ</mi> </math></EquationSource> </InlineEquation> channel widths in a Ni-based single-crystal superalloy. Intensity ratio analysis results reveal that, in the dendritic region, increasing <InlineEquation ID="IEq10"> <EquationSource Format="TEX">$\upgamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">γ</mi> </math></EquationSource> </InlineEquation> channel width is accompanied by a synchronous increase in Co and Cr enrichment in the <InlineEquation ID="IEq11"> <EquationSource Format="TEX">$\upgamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">γ</mi> </math></EquationSource> </InlineEquation> phase and an associated broadening of the interface. Furthermore, subset geometric phase results demonstrate that the absolute value of the strain field minimum decreases with increasing interface width in both dendritic and inter-dendritic regions with different material conditions. A linear relationship between interface width and local strain is identified, indicating the role of interface width. These findings establish a direct link between elemental segregation, interface width, and local strain at the <InlineEquation ID="IEq12"> <EquationSource Format="TEX">$\upgamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">γ</mi> </math></EquationSource> </InlineEquation>/<InlineEquation ID="IEq13"> <EquationSource Format="TEX">$\upgamma ^{\prime }$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi mathvariant="normal">γ</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation> interface, clarifying the role of heat treatment in regulating interfacial strain accommodation in Ni-based single-crystal superalloys.</p> Graphical abstract

Quantitative characterization of $\upgamma$/$\upgamma ^{\prime }$ interface widths and strains in a Ni-based single-crystal superalloy with aberration-corrected STEM and subset geometric phase analysis

期刊论文
发表日期：

2026年3月10日

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Xiao Han,
Miao Li,
Ruijun He,
Lingli Kong,
Kenan Cao,
Hongye Zhang,
Chao Ma,
Zenan Yang

摘要

Local strain and misfit-induced internal stress at the $\upgamma$ $γ$ / $\upgamma ^{\prime }$ $γ^{'}$ interface of Ni-based single-crystal superalloys play a critical role in dislocation evolution, creep performance, and recrystallization behavior. Although microsegregation at the interface and macroscopic residual stress can be characterized with high precision, a direct and quantitative correlation between local elemental segregation and nanoscale lattice strain at the $\upgamma$ $γ$ / $\upgamma ^{\prime }$ $γ^{'}$ interface remains insufficiently understood. In this paper, scanning transmission electron microscopy combined with subset geometric phase analysis was used to investigate the microsegregation, interface widths, and full-field strains of interface transition regions with different $\upgamma$ $γ$ channel widths in a Ni-based single-crystal superalloy. Intensity ratio analysis results reveal that, in the dendritic region, increasing $\upgamma$ $γ$ channel width is accompanied by a synchronous increase in Co and Cr enrichment in the $\upgamma$ $γ$ phase and an associated broadening of the interface. Furthermore, subset geometric phase results demonstrate that the absolute value of the strain field minimum decreases with increasing interface width in both dendritic and inter-dendritic regions with different material conditions. A linear relationship between interface width and local strain is identified, indicating the role of interface width. These findings establish a direct link between elemental segregation, interface width, and local strain at the $\upgamma$ $γ$ / $\upgamma ^{\prime }$ $γ^{'}$ interface, clarifying the role of heat treatment in regulating interfacial strain accommodation in Ni-based single-crystal superalloys.

Graphical abstract

Quantitative characterization of \(\upgamma\)/\(\upgamma ^{\prime }\) interface widths and strains in a Ni-based single-crystal superalloy with aberration-corrected STEM and subset geometric phase analysis

摘要