The durability of thermal barrier coating (TBC) systems is strongly influenced by the interaction between oxidation of the metallic bond coat and its mechanical behavior. While the response of bond coats under isothermal monotonic loading has been widely studied, the effect of thermal cycling remains poorly understood, even though cyclic loading naturally arises from the mismatch in coefficients of thermal expansion between the ceramic top coat, thermally grown oxide, metallic bond coat, and the superalloy substrate. In this work, high-energy X-ray diffraction was used to investigate the strain and stress evolution in the <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\beta $</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation>-(Ni, Pt)Al bond coat of a standard TBC deposited on a nickel-based single-crystal superalloy during thermal cycling. Before in situ cycling, some of the studied specimens were aged through long furnace cycles. Strains and stresses in the <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$\beta $</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation> phase were quantified in situ using the <InlineEquation ID="IEq5"> <EquationSource Format="TEX">${\hbox {sin}}^{2}\psi $</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mrow> <mtext>sin</mtext> </mrow> <mn>2</mn> </msup> <mi>ψ</mi> </mrow> </math></EquationSource> </InlineEquation> method combined with micromechanical modeling. The results reveal that plastic deformation in <InlineEquation ID="IEq6"> <EquationSource Format="TEX">$\beta $</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation> is strongly controlled by evolving interfacial effects and by the cyclic <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$\beta \rightleftharpoons \gamma '$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>β</mi> <mo stretchy="false">⇌</mo> <msup> <mi>γ</mi> <mo>′</mo> </msup> </mrow> </math></EquationSource> </InlineEquation> phase transformation during thermal cycling. These mechanisms govern the accumulation of plastic strain in <InlineEquation ID="IEq8"> <EquationSource Format="TEX">$\beta $</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation> and may promote rumpling, spallation, and ultimately TBC degradation. This study provides new mechanistic insight into bond-coat plasticity under thermal cycling.

In Situ Investigation of Plasticity Mechanisms of the $\beta $ Phase in (Ni, Pt)Al Bond Coats During Thermal Cycling by High-Energy X-Ray Diffraction

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2026年1月26日

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Mathias Lamari,
Lara Mahfouz,
Damien Texier,
Loïc Courtois,
Sylvain Gailliegue,
Andrew King,
Henry Proudhon,
Vincent Maurel

摘要

The durability of thermal barrier coating (TBC) systems is strongly influenced by the interaction between oxidation of the metallic bond coat and its mechanical behavior. While the response of bond coats under isothermal monotonic loading has been widely studied, the effect of thermal cycling remains poorly understood, even though cyclic loading naturally arises from the mismatch in coefficients of thermal expansion between the ceramic top coat, thermally grown oxide, metallic bond coat, and the superalloy substrate. In this work, high-energy X-ray diffraction was used to investigate the strain and stress evolution in the $\beta $ $β$ -(Ni, Pt)Al bond coat of a standard TBC deposited on a nickel-based single-crystal superalloy during thermal cycling. Before in situ cycling, some of the studied specimens were aged through long furnace cycles. Strains and stresses in the $\beta $ $β$ phase were quantified in situ using the ${\hbox {sin}}^{2}\psi $ ${sin}^{2} ψ$ method combined with micromechanical modeling. The results reveal that plastic deformation in $\beta $ $β$ is strongly controlled by evolving interfacial effects and by the cyclic $\beta \rightleftharpoons \gamma '$ $β ⇌ γ^{'}$ phase transformation during thermal cycling. These mechanisms govern the accumulation of plastic strain in $\beta $ $β$ and may promote rumpling, spallation, and ultimately TBC degradation. This study provides new mechanistic insight into bond-coat plasticity under thermal cycling.

In Situ Investigation of Plasticity Mechanisms of the \(\beta \) Phase in (Ni, Pt)Al Bond Coats During Thermal Cycling by High-Energy X-Ray Diffraction

摘要