| 1. |
- Cui, Luqing, et al.
(författare)
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A new approach for determining GND and SSD densities based on indentation size effect : An application to additive-manufactured Hastelloy X
- 2022
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Ingår i: Journal of Materials Science & Technology. - : Elsevier. - 1005-0302. ; 96, s. 295-307
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Tidskriftsartikel (refereegranskat)abstract
- Dislocation plays a crucial role in controlling the strength and plasticity of bulk materials. However, determining the densities of geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs) is one of the classical problems in material research for several decades. Here, we proposed a new approach based on indentation size effect (ISE) and strengthening theories. This approach was performed on a laser powder bed fused (L-PBF) Hastelloy X (HX), and the results were verified by the Hough-based EBSD and modified Williamson–Hall (m-WH) methods. Furthermore, to better understand the new approach and essential mechanisms, an in-depth investigation of the microstructure was conducted. The distribution of dislocations shows a clear grain orientation-dependent: low density in large <101> preferentially orientated grains while high density in fine <001> orientated grains. The increment of strengthening in L-PBF HX is attributed to a huge amount of edge-GNDs. Planar slip is the main operative deformation mechanism during indentation tests, and the slip step patterns depend mostly on grain orientations and stacking fault energy. This study provides quantitative results of GND and SSD density for L-PBF HX, which constructs a firm basis for future quantitative work on other metals with different crystal structures.
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| 2. |
- Cui, Luqing, et al.
(författare)
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Cyclic Response of Additive Manufactured 316L Stainless Steel : The Role of Cell Structures
- 2021
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Ingår i: Scripta Materialia. - : Elsevier. - 1359-6462 .- 1872-8456. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- We report the effect of cell structures on the fatigue behavior of additively manufactured (AM) 316L stainless steel (316LSS). Compared with the cell-free samples, the fatigue process of fully cellular samples only consists of steady and overload stages, without an initial softening stage. Moreover, the fully cellular sample possesses higher strength, lower cyclic softening rate and longer lifetime. Microscopic analyses show no difference in grain orientations, dimensions, and shapes. However, the fully cellular samples show planar dislocation structures, whereas the cell-free samples display wavy dislocation structures. The existence of cell structures promotes the activation of planar slip, delays strain localization, and ultimately enhances the fatigue performance of AM 316LSS.
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| 3. |
- Sun, Xiaoyu, et al.
(författare)
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Impeding the γ' depletion during the interdiffusion between bond coatings and superalloys via introduction of tantalum in bond coatings
- 2023
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Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- The use of aluminiferous coatings profoundly improves the service life of superalloys but leads to microstructural degradation of superalloys and thus loss of mechanical properties. In this study, we mod- ified MCrAlY coatings by adding Ta to reduce the interdiffusion effect on substrate alloys. This strategy was verified by 2000 h/1100 °C oxidation tests in two Ta-containing MCrAlY-IN792 systems. The system with 3.3 wt% Ta MCrAlY exhibits an outstanding resistance to c0 depletion in the substrate and compa- rable oxidation property in comparison with a reference system of Ta-free MCrAlY-IN792. Increasing Ta to 7.4 wt% results in reduced oxidation resistance. Thermodynamic simulations revealed the phase- transformation mechanism induced by initial interdiffusion, uncovering the cause of c0 depletion in the substrate and the mechanism behind improving resistance to c0 depletion by Ta addition.
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| 4. |
- Sun, Xiaoyu
(författare)
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Performance of High-temperature Coatings : Oxidation and Interdiffusion
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of aluminiferous coatings profoundly improves the service life of superalloys but leads to the microstructural degradation of superalloys and thus the loss of mechanical properties. To solve this trade-off, two strategies were employed in this research.At first, we modified MCrAlY coatings by inducing Ta to reduce the interdiffusion effect on substrate alloys. This strategy was verified by 2000 h/1100 °C oxidation tests in two Ta-containing MCrAlY-IN792 systems. The system with 3.3 wt.% Ta MCrAlY displays an outstanding resistance to γ′ depletion in the substrate and comparable oxidation property in comparison with a reference system of Ta-free MCrAlY-IN792. Increasing Ta to 7.4 wt.% results in reduced oxidation resistance. Thermodynamic simulations revealed the phase-transformation mechanism induced by initial interdiffusion, uncovering the cause of γ′ depletion in the substrate and the mechanism behind improving resistance to γ′ depletion by Ta addition.In addition, we developed novel Y-doped AlCoCrFeNi high-entropy alloys by tuning Al/Cr ratio ACR. After a long-term isothermal test in air at 1100 °C up to 1000 h, the higher ACR alloy displayed a stronger oxidation resistance at the early oxidation stage, whereas a contrary result could be detected in the later stage. The microstructural analysis confirmed that the fast growth of spinel dominated the early oxidation process, leading to higher oxidation rate of the lower ACR alloys. The later stage was governed by the growth of Al2O3. Lager size Al2O3 gain formed on the lower ACR alloy impeded the inward diffusion of oxygen and thus reduced the oxidation rate, which was further verified by our thermodynamic calculations.
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| 5. |
- Sun, Xiaoyu, et al.
(författare)
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Revealing microstructural degradation mechanism induced by interdiffusion between Amdry365 coating and IN792 superalloy
- 2024
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Ingår i: Materials & design. - : ELSEVIER SCI LTD. - 0264-1275 .- 1873-4197. ; 241
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Metallic coatings are widely employed to improve the oxidation resistance of superalloys. However, the interdiffusion between the metallic coatings and the superalloys leads to microstructural degradation in both. Some of the underlying degradation mechanisms are still elusive, e.g., the γ′ (Ni3Al) phase depletion in superalloys, where a large amount of γ′ precipitates are dissolved in the γ matrix even though the incoming Al from coatings indeed increases the Al content. Here, we investigated the interdiffusion behavior between the Amdry365 coating and the IN792 superalloy at 1100 °C, using multiple microscopic techniques and thermodynamics calculations. Our results showed an excellent agreement between experiments and thermodynamics simulations, indicating the dominant role of Al on the initial diffusion-induced phase transitions. We proposed the Al-Cr interference effect to account for the pile-up behavior of Cr and the reduced Al content near the coating/superalloy interface. The local phase equilibrium calculations revealed that the γ′ depletion in the superalloy is primarily attributed to the loss of γ′-forming elements, such as Ta and Ti. Our findings opened up an avenue for studies on the superalloy/coating interdiffusion, contributing to reducing this damaging impact.
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| 6. |
- Sun, Xiaoyu, et al.
(författare)
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Revealing microstructural degradation mechanism induced by interdiffusion between Amdry365 coating and IN792 superalloy
- 2024
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Ingår i: Materials and Design. - : ELSEVIER SCI LTD. - 1873-4197 .- 0264-1275. ; 241
-
Tidskriftsartikel (refereegranskat)abstract
- Metallic coatings are widely employed to improve the oxidation resistance of superalloys. However, the interdiffusion between the metallic coatings and the superalloys leads to microstructural degradation in both. Some of the underlying degradation mechanisms are still elusive, e.g., the γ′ (Ni3Al) phase depletion in superalloys, where a large amount of γ′ precipitates are dissolved in the γ matrix even though the incoming Al from coatings indeed increases the Al content. Here, we investigated the interdiffusion behavior between the Amdry365 coating and the IN792 superalloy at 1100 °C, using multiple microscopic techniques and thermodynamics calculations. Our results showed an excellent agreement between experiments and thermodynamics simulations, indicating the dominant role of Al on the initial diffusion-induced phase transitions. We proposed the Al-Cr interference effect to account for the pile-up behavior of Cr and the reduced Al content near the coating/superalloy interface. The local phase equilibrium calculations revealed that the γ′ depletion in the superalloy is primarily attributed to the loss of γ′-forming elements, such as Ta and Ti. Our findings opened up an avenue for studies on the superalloy/coating interdiffusion, contributing to reducing this damaging impact.
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| 7. |
- Sun, Xiaoyu, et al.
(författare)
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Tuning Mo/W ratio to improve high temperature oxidation resistance of single crystal nickel base superalloys
- 2024
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Ingår i: Materials Today Communications. - : ELSEVIER. - 2352-4928. ; 38
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Tidskriftsartikel (refereegranskat)abstract
- The effect of different Mo/W ratios of three single crystal nickel base superalloys on the oxidation behavior was investigated at 1100 degrees C. Both isothermal and cyclic oxidation tests showed that increasing Mo/W ratio corresponds to lower weight change and improved resistance. The microscopic observation uncovers that the harmful effect of Mo is limited by the dense Al2O3 scale. In contrast, excessive W leads to fast growth of interlayer and its premature spallation. This research proposes and verifies a new way to improve oxidation resistance of alloy, namely, balancing the harmful effect of refractory elements.
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| 8. |
- Wang, Huan, et al.
(författare)
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Boosting the Electrochemical Performance of PI-5-CA/C-SWCNT Nanohybrid for Sensitive Detection of E. coli O157:H7 From the Real Sample
- 2022
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Ingår i: Frontiers in Chemistry. - : Frontiers Media SA. - 2296-2646. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Redox activity is an important indicator for evaluating electrochemical biosensors. In this work, we have successfully polymerized indole-5-carboxylic acid into poly-5-carboxyindole nanomaterials (PI-5-CA), using its superior redox activity, and introduced carboxylated single-walled carbon nanotubes (C-SWCNTs) to synthesize a composite material. Finally, a synthesized composite material was used for the modification of the glass carbon electrode to fabricate the PI-5-CA/C-SWCNTs/GCE-based immunosensor and was successfully applied for the sensitive detection of E. coli O157:H7. The fabricated immunosensor exhibited an outstanding electrocatalytic activity toward the detection of E. coli O157:H7 with a remarkably lowest limit of detection (2.5 CFU/ml, LOD = 3 SD/k, n = 3) and has a wide linear range from 2.98x10(1) to 2.98x10(7) CFU/ml. Inspired from the excellent results, the fabricated electrode was applied for the detection of bacteria from real samples (water samples) with a good recovery rate (98.13-107.69%) as well as an excellent stability and specificity. Owing to its simple preparation, excellent performance, and detection time within 30 min, our proposed immunosensor will open a new horizon in different fields for the sensitive detection of bacteria from real samples.
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| 9. |
- Wang, Xiaoyu, et al.
(författare)
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Associations of Insomnia With Insulin Resistance Traits : A Cross-sectional and Mendelian Randomization Study
- 2023
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 108:8, s. e574-e582
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Tidskriftsartikel (refereegranskat)abstract
- Context: Insomnia is associated with insulin resistance (IR) in observational studies; however, whether insomnia is causally associated with IR remains unestablished.Objective: This study aims to estimate the causal associations of insomnia with IR and its related traits.Methods: In primary analyses, multivariable regression (MVR) and 1-sample Mendelian randomization (1SMR) analyses were performed to estimate the associations of insomnia with IR (triglyceride-glucose index and triglyceride to high-density lipoprotein cholesterol [TG/HDL-C] ratio) and its related traits (glucose level, TG, and HDL-C) in the UK Biobank. Thereafter, 2-sample MR (2SMR) analyses were used to validate the findings from primary analyses. Finally, the potential mediating effects of IR on the pathway of insomnia giving rise to type 2 diabetes (T2D) were examined using a 2-step MR design.Results: Across the MVR, 1SMR, and their sensitivity analyses, we found consistent evidence suggesting that more frequent insomnia symptoms were significantly associated with higher values of triglyceride-glucose index (MVR, beta = 0.024, P < 2.00E-16; 1SMR, beta = 0.343, P < 2.00E-16), TG/HDL-C ratio (MVR, beta = 0.016, P = 1.75E-13; 1SMR, beta = 0.445, P < 2.00E-16), and TG level (MVR, beta = 0.019 log mg/dL, P < 2.00E-16, 1SMR: beta = 0.289 log mg/dL, P < 2.00E-16) after Bonferroni adjustment. Similar evidence was obtained by using 2SMR, and mediation analysis suggested that about one-quarter (25.21%) of the association between insomnia symptoms and T2D was mediated by IR.Conclusions: This study provides robust evidence supporting that more frequent insomnia symptoms are associated with IR and its related traits across different angles. These findings indicate that insomnia symptoms can be served as a promising target to improve IR and prevent subsequent T2D.
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| 10. |
- Xie, Haibing, et al.
(författare)
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Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells
- 2021
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Ingår i: Joule. - : CELL PRESS. - 2542-4351. ; 5:5, s. 1246-1266
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Tidskriftsartikel (refereegranskat)abstract
- Understanding defects is of paramount importance for the development of stable halide perovskite solar cells (PSCs). However, isolating their distinctive effects on device efficiency and stability is currently a challenge. We report that adding the organic molecule 3-phosphonopropionic acid (H3pp) to the halide perovskite results in unchanged overall optoelectronic performance while having a tremendous effect on device stability. We obtained PSCs with similar to 21% efficiency that retain similar to 100% of the initial efficiency after 1,000 h at the maximum power point under simulated AM1.5G illumination. The strong interaction between the perovskite and the H3pp molecule through two types of hydrogen bonds (H center dot center dot center dot I and O center dot center dot center dot H) leads to shallow point defect passivation that has a significant effect on device stability but not on the non-radiative recombination and device efficiency. We expect that our work will have important implications for the current understanding and advancement of operational PSCs.
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