Evolution of Micro-Pores in a Single-Crystal Nickel-Based Superalloy During Solution Heat Treatment

Li, Xiangwei; Wang, Li; Dong, Jianshu; Lou, Langhong; Zhang, Jian

doi:10.1007/s11661-017-4057-2

Cited by 29 publications

(10 citation statements)

References 21 publications

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“…Although many studies have reported the growth of micro-pores at high temperatures [ 116 , 117 ], the S-pores and H-pores in these studies were treated as the same micro-pores. How the S-pore and H-pore evolve and their respective fundamental mechanisms are still unsolved issues [ 118 ].…”

Section: Lb-xrt Examplesmentioning

confidence: 99%

“…After that, the samples were taken out to be re-scanned using XRT. This process was repeated several times with the only difference of the solution heat treatment was time, by substituting 4, 7, 12, and 20 h for one hour [ 118 ]. The XRT volume renderings of the micro-pores in the same sample showed the characteristics during the solution heat treatment in Figure 5 .…”

Section: Lb-xrt Examplesmentioning

confidence: 99%

“… XRT volume renderings of micro-pores in a same sample with a heat treatment at 1603 K for ( a ) 0 h, ( b ) 1 h, ( c ) 4 h, ( d ) 7 h, ( e ) 12 h, and ( f ) 20 h. The equivalent diameter (μm) of the S-pores is also given [ 118 ]. …”

Section: Figurementioning

confidence: 99%

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Correlation of Materials Property and Performance with Internal Structures Evolvement Revealed by Laboratory X-ray Tomography

Zhang

Wang

2018

Materials

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Although X-rays generated from a laboratory-based tube cannot be compared with synchrotron radiation in brilliance and monochromaticity, they are still viable and accessible in-house for ex situ or interrupted in situ X-ray tomography. This review mainly demonstrates recent works using laboratory X-ray tomography coupled with the measurements of properties or performance testing under various conditions, such as thermal, stress, or electric fields. Evolvements of correlated internal structures for some typical materials were uncovered. The damage features in a graded metallic 3D mesh and a metallic glass under mechanical loading were revealed and investigated. Micro-voids with thermal treatment and void healing phenomenon with electropulsing were clearly demonstrated and quantitatively analyzed. The substance transfer around an electrode of a Li-S battery and the protective performance of a Fe-based metallic glass coating on stainless steel were monitored through electrochemical processes. It was shown that in situ studies of the laboratory X-ray tomography were suitable for the investigation of structure change under controlled conditions and environments. An extension of the research for in situ laboratory X-ray tomography can be expected with supplementary novel techniques for internal strain, global 3D grain orientation, and a fast tomography strategy.

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Section: Lb-xrt Examplesmentioning

confidence: 99%

Section: Lb-xrt Examplesmentioning

confidence: 99%

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Correlation of Materials Property and Performance with Internal Structures Evolvement Revealed by Laboratory X-ray Tomography

Zhang

Wang

2018

Materials

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“…

Single crystals of nickel-base superalloys are commonly used as blade material in the hottest sections of gas turbines or aero engines. After casting and heat treatment, the components contain pores of various sizes [1][2][3] : Larges irregular pores of size up to 50 μm form during solidification (S-pores, see Figure 1a) and small round pores of size up to 10 μm form during the homogenization heat treatment (H-pores, see Figure 1b). It has been shown (see, e.g., the study by Epishin [4] ) that pores are detrimental to the fatigue strength of the alloys as they favor crack initiation.

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confidence: 99%

Simulation of Hot Isostatic Pressing in a Single‐Crystal Ni Base Superalloy with the Theory of Continuously Distributed Dislocations Combined with Vacancy Diffusion

2022

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Single‐crystal components made of nickel base superalloys contain pores after casting and homogenization heat treatment. Hot isostatic pressing (HIP), which is carried above the γ′‐solvus temperature of the alloy, is industrially applied to reduce porosity. A modeling of HIP based on continuously distributed dislocations is developed in a 2D setting. Glide and climb of straight‐edge dislocations, as well as vacancy diffusion, are the deformation mechanisms taken into account. Thereby, dislocation glide is controlled by dragging a cloud of large atoms, and climb is controlled by vacancy diffusion. Relying on previous investigations of the creep behavior at HIP temperatures, it is assumed that new dislocations are nucleated at low‐angle boundaries (LAB) and move through subgrains until they either reach the opposite LABs or react with other dislocations and annihilate. Vacancies are created at the pore surface and diffuse through the alloy until they are either consumed by climbing dislocations or disappear at the LABs. The field equations are solved by finite elements. It is shown that pore shrinking is mostly controlled by vacancy diffusion as the shear stresses at the LABs are too low to nucleate a sufficient amount of dislocations.

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“…Figure 5. XRT volume renderings of micro-pores in a same sample with a heat treatment at 1603 K for (a) 0 h, (b) 1 h, (c) 4 h, (d) 7 h, (e) 12 h, and (f) 20 h. The equivalent diameter (μm) of the S-pores is also given[118].…”

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confidence: 99%

In-Situ X-Ray Tomographic Study of Materials

Maire¹,

Adrien²,

Withers³

2020

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X-ray computed tomography (CT) is advancing apace both in terms of the spatial resolution that can be achieved and the rate at which the radiographs necessary to reconstruct a 3D image can be collected. These advances combined with the fact that CT is inherently non-destructive mean that X-ray CT is moving simply from the collection of 3D images to the acquisition of 3D movies. Whether it is to collect information of rapidly changing behaviors, such as fracture, where live streaming of many 1000's of radiographs per second are needed to follow the events in situ, exploiting the intensity of a synchrotron X-ray source, or the longer timescales associated with long term oxidation, where time-lapse ex situ observations made by laboratory CT sources, X-ray CT provides unique insights into the behavior of natural and man-made materials that simply cannot be obtained by any other means.This book is a collection of chapters. It celebrates the possibilities for gaining inside information through time resolved X-ray CT looking both at the technical developments and opportunities for improving the quality and quantification of the image data we collect to the range of questions that X-ray CT can shine light upon. It is clear from this collection that many different environments and external constraints can be applied to the materials in situ whether to form the material or to observe its degradation or healing. We are sure that these chapters only represent the tip of the iceberg and that time-resolved X-ray CT, whether exploiting the intensity of a synchrotron or the accessibility or laboratory CT systems, will continue to develop into an indispensable characterization tool, alongside optical and electron microscopy. Further, we believe that the imaging modes, whether to detect subtle changes in phase, crystallographic structure or to fingerprint the elements contained in phases, will expand to provide an even richer picture of the internal structure of materials and their evolution over time than we can achieve today. We hope that this book shows the future or time resolved imaging is indeed very bright.

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Evolution of Micro-Pores in a Single-Crystal Nickel-Based Superalloy During Solution Heat Treatment

Cited by 29 publications

References 21 publications

Correlation of Materials Property and Performance with Internal Structures Evolvement Revealed by Laboratory X-ray Tomography

Correlation of Materials Property and Performance with Internal Structures Evolvement Revealed by Laboratory X-ray Tomography

Simulation of Hot Isostatic Pressing in a Single‐Crystal Ni Base Superalloy with the Theory of Continuously Distributed Dislocations Combined with Vacancy Diffusion

In-Situ X-Ray Tomographic Study of Materials

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