The internal oxide precipitates were supposed to be spherical in Wagner’s original theory,while the fol-lowing research demonstrated that this assumption is an exception rather than the truth,which caused deviations ...The internal oxide precipitates were supposed to be spherical in Wagner’s original theory,while the fol-lowing research demonstrated that this assumption is an exception rather than the truth,which caused deviations in the application of this theory.In this study,the internal oxide precipitates have a needle-like and a near-spherical morphology in a Fe-9Cr ferritic and a Fe-17Cr-9Ni austenitic steels after expo-sure to 600℃ deaerated steam for 600 h,respectively.The nano-to-atomic scale characterization shows that the morphology of the internal oxide precipitates is controlled by the structure of the interfaces be-tween the metal matrix and the internal oxide,while the interface structure is mainly affected by the crystallographic structure of the two phases and their orientation relationship.In addition,the internal oxide precipitation-induced volume expansion and the outward Fe diffusion-induced volume shrink oc-cur simultaneously during the oxidation process.The stress status in the internal oxidation zone(IOZ)is the competing result of the two factors,which could dynamically affect the high-temperature oxidation.The results obtained in this study suggest that there is potential to control the distribution,morphology,and interface structure of the internal oxide precipitates by selecting appropriate base metal and internal oxide-forming element,in order to obtain better high-temperature oxidation-resistant materials.展开更多
基金This work was financially supported by National Key Re-search and Development Program of China(No.2018YFE0116200)Shanghai Pujiang Program(No.21PJ1406400)+1 种基金EPSRC(Nos.EP/K040375/1,EP/N010868/1,and EP/R009392/1)Prof.Lefu Zhang is acknowledged for providing the samples used in this study.In-strumental Analysis Center of SJTU is also gratefully acknowledged.The atom probe facilities at the University of Oxford are funded by the EPSRC(No.EP/M022803/1).
文摘The internal oxide precipitates were supposed to be spherical in Wagner’s original theory,while the fol-lowing research demonstrated that this assumption is an exception rather than the truth,which caused deviations in the application of this theory.In this study,the internal oxide precipitates have a needle-like and a near-spherical morphology in a Fe-9Cr ferritic and a Fe-17Cr-9Ni austenitic steels after expo-sure to 600℃ deaerated steam for 600 h,respectively.The nano-to-atomic scale characterization shows that the morphology of the internal oxide precipitates is controlled by the structure of the interfaces be-tween the metal matrix and the internal oxide,while the interface structure is mainly affected by the crystallographic structure of the two phases and their orientation relationship.In addition,the internal oxide precipitation-induced volume expansion and the outward Fe diffusion-induced volume shrink oc-cur simultaneously during the oxidation process.The stress status in the internal oxidation zone(IOZ)is the competing result of the two factors,which could dynamically affect the high-temperature oxidation.The results obtained in this study suggest that there is potential to control the distribution,morphology,and interface structure of the internal oxide precipitates by selecting appropriate base metal and internal oxide-forming element,in order to obtain better high-temperature oxidation-resistant materials.
