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Microstructure evolution of K439B Ni-based superalloy casting with varying cross-sections by experiments and simulations

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Transactions of Nonferrous Metals Society of China 2025年第4期35卷 1182-1196页

作者： Da-shan SUI De-peng ZHOU Yang LIU Yu SHAN An-ping DONG Institute of Forming Technology&Equipment School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200030China Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Casting experiments and macro-micro numerical simulations were conducted to examine the microstructure characteristics of K439B nickel-based superalloy casting with varying cross-sections during the gravity investment casting ***,microstructure analysis was conducted on the casting using scanning electron microscopy(SEM)and electron backscatter diffraction(EBSD).Subsequently,calculation of the phase diagram and differential scanning calorimetry(DSC)tests were conducted to determine the macro-micro simulation parameters of the K439B alloy,and the cellular automaton finite element(CAFE)method was employed to develop macro-micro modeling of K439B nickel-based superalloy casting with varying *** experimental results revealed that the ratio of the average grain area increased from the edge to the center of the sections as the ratio of the cross-sectional area *** simulation results indicated that the average grain area increased from 0.885 to 0.956 mm^(2)as the ratio of the cross-sections increased from 6꞉1 to 12꞉*** experiment and simulation results showed that the grain size became more heterogeneous and the grain shape became more irregular with an increase in the ratio of the cross-sectional area of the *** modeling was an effective method to simulate the microstructure evolution of the K439B alloy and ensure the accuracy of the simulation.

关键词： K439B nickel-based superalloy cellular automaton cellular automaton finite element method varying cross-section investment casting microstructure evolution

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Enhancing corrosion resistance of MAO coatings on Al alloy LY12 through in situ co-doping with zinc phosphate and cerium phosphate

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Corrosion Communications 2025年第1期17卷 35-43页

作者： Chao Yang Tao Ying Aihui Huang Jian Huang Pinghu Chen Paul K.Chu Xiaoqin Zeng National Engineering Research Center of Light Alloy Net Forming School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai Key Laboratory of Advanced High-Temperature Materials and Precision Forming School of Materials Science and Engineering Shanghai Jiao Tong University Department of Chemistry University of Munich(LMU) College of Mechanical Engineering Key Laboratory of Hunan Province of Equipment Safety Service Technology under Extreme Environment University of South China Department of Physics Department of Materials Science&Engineering and Department of Biomedical Engineering City University of Hong Kong

Corrosion of aluminum（Al） alloys during service limits many applications. Micro-arc oxidation（MAO） coatings can enhance corrosion resistance, but porous defects in the films undermine their effectiveness. Here, by mixing a phosphate electrolyte with soluble Zn and Ce salts, zinc phosphate and cerium phosphate co-doped MAO corrosion-resistant coating is prepared on Al alloy LY12. Zinc phosphate and cerium phosphate are incorporated in situ to form an amorphous encapsulated nanocrystalline structure. During long-term corrosion, Zn2+is released and deposited as corrosion products Zn（OH）2to cover weak corrosion micro-regions in the coating. Simultaneously, Ce3+released from MAO coating co-doped with zinc phosphate/cerium phosphate forms Zn（OH）2/Ce（OH）3due to the small solubility product Kspto further enhance corrosion resistance. Compared to pristine Al alloy,corrosion potential increases from -1.306 to -0.819 VSCE, and corrosion current density decreases by 4 orders of magnitude from 2.6 × 10-6to 2.5 × 10-10A·cm-2. Co-doped MAO coating significantly enhances corrosion resistance of Al alloy LY12 and shows great potential for a wide range of applications.

关键词： Aluminum alloys Micro-arc oxidation coating Corrosion resistance Zinc phosphate Cerium phosphate

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Thermal-solutal convection-induced low-angle grain boundaries in single-crystal nickel-based superalloy solidification

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材料科学技术（英文版） 2025年第5期208卷 214-229页

作者： Luwei Yang Neng Ren Jun Li Chinnapat Panwisawas Yancheng Zhang Mingxu Xia Hongbiao Dong Jianguo Li School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai 200240China School of Engineering and Materials Science Queen Mary University of LondonLondon E14NSUnited Kingdom Mines paris PSL UniversityCentre de Mise en Forme des Matériaux(CEMEF)UMR CNRS 7635Sophia AntipolisFrance School of Engineering University of LeicesterLeicester LE17RHUnited Kingdom

Low-angle grain boundaries(LAGBs)are one of the solidification defects in single-crystal nickel-based su-peralloys and are detrimental to the mechanical *** formation of LAGBs is related to dendrite deformation,while the mechanism has not been fully understood at the *** this work,a model coupling dendrite growth,thermal-solutal-fluid flow,thermal stress and flow-induced dendrite deforma-tion via cellular automaton-finite volume method and finite element method is developed to study the formation of LAGBs in single crystal *** reveal that the bending of dendrites is primar-ily attributed to the thermal-solutal convection-induced dendrite *** mechanical stress of dendrite deformation develops and stabilises as solidification *** the width of the mushy zone gets stable,stresses are built up and then dendritic elastoplastic bending occurs at some thin primary dendrites with the wider inter-dendritic *** are three characteristic zones of stress distribu-tion along the solidification direction:(i)no stress concentration in the fully solidified regions;(ii)stress developing in the primary dendrite bridging region,and(iii)stress decrease in the inter-dendritic uncon-tacted *** stresses reach maximum near the initial dendrite bridging *** lower temper-ature gradients,the finer primary dendritic trunks and sudden reductions in local dendritic trunk radius jointly promote the elastoplastic deformation of the *** measures are suggested to reduce LAGBs.

关键词： Dendrite deformation Low-angle grain boundary Misorientation Thermal-solutal convection Superalloys

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Engineering design of feedstock powder and relevant thermal-mechanical performance of thermal/environmental barrier coatings

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Journal of advanced Ceramics 2025年第2期14卷 37-56页

作者： Xinchang Feng Fangwei Guo Lirong Luo Yuzhang Wang Yun Long Xiaofeng Zhao Fei Pan Lei Guo Qingfeng Zeng Jing Feng Chunlei Wan Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National Engineering Research Center of Special Equipment and Power System for Ship and Marine Engineering Shanghai 200030China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Advanced Nuclear Energy Technology Nuclear Power Institute of ChinaChengdu 610213China Innovative Sensor Technology IST AG Ebnat-Kappel 9642Switzerland School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianmushan Laboratory Hangzhou 311115China School of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

The development of aeroengine with a high thrust-weight ratio poses great challenges for current top-coating thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs) in service. Medium/high-entropy ceramics are highly promising candidate material for advanced TBCs/EBCs owing to their low thermal conductivity, high melting point, high-temperature stability, and calcium–magnesium–alumino–silicate (CMAS) resistance. Most feedstock powder used for medium/high-entropy TBCs/EBCs is prepared via traditional spray drying, which cannot fully exploit the advantages of multicomponent ceramics. The density, sphericity, inner structure, and flowability of feedstock powder affect their melting state during the thermal spraying process, which strongly affects the microstructure and properties of the deposited coatings. Therefore, the deposited coatings exhibit phase segregation, amorphous phases, and microstructure defects owing to unpredictable variations in feedstock powder with random morphologies and structures. Here, the structure and properties of feedstock powder prepared by state-of-the-art granulation technologies and their influences on the deposited coatings were systematically investigated, which can provide guidance for configuration optimization of feedstock powder and the manufacturing accuracy of the deposited coating. This review aims to bridge the gap between cutting-edge ceramics and advanced engineering technologies, thus providing concrete background knowledge and crucial guidelines for designing and developing TBCs/EBCs.

关键词： thermal/environmental barrier coatings(TBCs/EBCs) spraying ceramic powder multiscale structure control high-entropy ceramics thermal-mechanical performance

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Influence of laser shock peening on microstructure and high-temperature oxidation resistance of Ti45Al8Nb alloy fabricated via laser melting deposition

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Transactions of Nonferrous Metals Society of China 2025年第1期35卷 157-168页

作者： Lu-lu JIANG Liang LAN Cheng-yan BAI Ru-yi XIN Shuang GAO Hao-yu WANG Bo HE Chao-yue CHEN Guo-xin LU Research Center of High-Temperature Alloy Precision Forming School of Materials Science and EngineeringShanghai University of Engineering ScienceShanghai 201620China State Key Laboratory of Advanced Special Steels School of Materials Science and EngineeringShanghai UniversityShanghai 200444China School of Materials Science and Engineering Shandong UniversityJinan 250061China

Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb *** microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb alloy before and after LSP were investigated by scanning electron microscopy,X-ray diffraction,and electron backscatter *** results indicated that the rate of mass gain in the as-deposited sample after LSP exhibited a decrease when exposed to an oxidation temperature of 900℃,implying that LSP-treated samples exhibited superior oxidation resistance at high temperatures.A gradient structure with a fine-grain layer,a deformed-grain layer,and a coarse-grain layer was formed in the LSP-treated sample,which facilitated the diffusion of the Al atom during oxidation,leading to the formation of a dense Al_(2)O_(3)layer on the *** mechanism of improvement in the oxidation resistance of the as-deposited Ti45Al8Nb alloy via LSP was discussed.

关键词： TiAl alloy laser melting deposition laser shock peening additive manufacturing oxidation resistance

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Effect of annealing temperature on microstructure and mechanical properties of a heavy cold-rolled Custom 465 maraging stainless steel

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materials Science and Engineering: A 2025年 936卷

作者： Fu, Tao Fu, Liming Qin, Dongyang Ye, Cong Ma, Shuo Wen, Mao Shan, Aidang School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Shanghai Key Laboratory of High-Temperature Materials and Precision Forming Shanghai Jiao Tong University Shanghai200240 China

In this study, we investigated the microstructure evolution and mechanical properties of heavy cold-rolled Custom 465 maraging stainless steel subjected to annealing treatments at various temperatures ranging from 300 to 1000 °C. The results indicate that the evolution of microstructure and mechanical behavior can be distinctly divided into three stages as the annealing temperature increases. In the aging stage (Stage A), when annealing temperature is below 550 °C, the synergistic effects of ultrafine lamella structure, high-density dislocations, and newly formed η-Ni3Ti precipitates contributed to the exceptional mechanical properties, demonstrating ultrahigh yield strength of 2011 MPa, ultimate tensile strength of 2034 MPa, and low uniform elongation of 0.42 % when annealed at 500 °C. In the overaging stage (Stage B), when annealing temperature is within the range of 600–700 °C, the primary microstructural changes observed are the formation of reverted austenite and the coarsening of the η-Ni3Ti precipitates, which exhibits low work hardening capacity and good elongation. In the recrystallization stage (Stage C), annealing above 750 °C allows for complete austenitization during the holding period, and the formation of fresh martensite. Annealing at 750 °C results in the austenite content of 84 vol%, with the average prior austenite grain size of 1.04 μm, whereas annealing temperature is above 850 °C, the increased prior austenite grain size leads to the formation of fresh martensite and results in mechanical properties similar to those of the undeformed Custom 465. In addition, in the heavy cold-rolled Custom 465, the precipitation phase transitions from η-Ni3Ti to Laves phase with increasing annealing temperature, with the transformation occurring at 700 °C. Moreover, the ultrafine refinement of prior austenite grain size effectively enhances the stability of austenite. These observations provide valuable insights into the microstructural design and control of ul

关键词： Tensile strength

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Superior mechanical properties for an additively manufactured crack-free Ni-based superalloy with an inherited metastable microstructure after heat treatment

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Journal of materials Research and Technology 2025年 36卷 8108-8121页

作者： Dongyu Wei Lu Shi Wenzhe Zhou Yusheng Tian Beiya Wang Rui Wang Jian He Decheng Kong Guoliang Zhu Baode Sun Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China Shanghai Aerospace System Engineering Institute Shanghai 201108 China China Aerosp Sci & Technology Corp Beijing Inst Space Long March Vehicle Beijing 100076 China

Localized non-equilibrium and rapid solidification usually generate a distinctive metastable microstructure in metals and alloys produced through the laser powder bed fusion. Therefore, it is crucial to modulate the printed microstructure for the final mechanical properties. Several heat treatment procedures were developed to control the cellular structure and carbides of the LPBF (Laser powder bed fusion) ZGH4142 alloy in this work. The relationship between heat treatment, microstructure, and mechanical properties was thoroughly investigated. It shows that traditional standard heat treatment is not the optimal approach for ZGH4142 alloy, and the specimens exhibit moderate high-temperature strength but reduced ductility after high-temperature heat treatment, owing to the presence of oversized carbides. However, directly aged ZGH4142 alloy (900 °C) demonstrates a superior combination of high-temperature ultimate tensile strength (139.7 MPa) and elongation (11.5 %) at 1100 °C. The preserved metastable cellular microstructures hinder dislocation transfer between adjacent cells and limit dislocation slipping within cells for the directly aged counterparts, and the fine carbides strengthen the grain boundary and prevent premature instability therein. The research findings provide valuable insights for exploring heat treatment processes to maintain the inherited metastable microstructure formed during the printing process for other AM Ni-based superalloys.

关键词： Inherited metastable microstructure Mechanical behavior Laser powder bed fusion Ni-based superalloy

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Enhanced heat transfer on hollow hierarchical nanowired surface during transient spray cooling of liquid nitrogen

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International Communications in Heat and Mass Transfer 2025年 165卷

作者： Fan, Yiming Su, Fengmin Peng, Jiahui Fan, Letian Chang, Chao Ji, Yulong Wen, Rongfu Zhu, Guoliang Institute of Marine Engineering and Thermal Science Dalian Maritime University Liaoning Province Dalian116026 China State Key Laboratory of Fine Chemicals Frontier Science Center for Smart Materials Dalian University of Technology Liaoning Province Dalian116024 China Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China

The liquid spreading and replenishment has a key effect on the performance of transient spray cooling. In this study, we used liquid nitrogen as the working fluid and conducted transient spray cooling experiments on four modified copper surfaces, including superhydrophilic surface, hydrophilic surface, smooth copper surface, and hollow hierarchical nanowired surface. The results show that increasing the single-scale surface hydrophilicity of the copper surface can effectively increase the critical heat flux (CHF) of liquid nitrogen transient spray cooling, due to the effective enhancement of evaporation heat transfer coefficient h. The multi-scale hollow hierarchical structure surface can further enhance the heat transfer of liquid nitrogen transient spray cooling, its cooling rate is accelerated 1.3 times, the CHF is increased 1.2 times and the maximum hMAX is increased 1.11 times that of the superhydrophilic surface. Through the calculation of the liquid film climb theory model, it was found that the liquid nitrogen film climbs at a speed of 48.10 m/s in the nanowired clusters. The ultrafast climb of liquid nitrogen film in hierarchical nanowires may be one of the main reasons for enhanced heat transfer. This study broadens the experimental database of hierarchical structure surfaces and new ideas on enhanced heat transfer during cryogenic spray cooling. © 2025 Elsevier Ltd

关键词： Nanowires

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Effect of building-height-dependent heat accumulation on microstructure and properties of Super Invar alloy fabricated by laser powder bed fusion

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materials Characterization 2025年 224卷

作者： Zhao, Renjie Shi, Lu Liu, Haihui Zhang, Lanting Feng, Kai Li, Zhuguo Xie, Renbiao Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Co. Ltd Shanghai200120 China Shanghai Aerospace System Engineering Institute Shanghai201108 China Shanghai Zhongchen Tobacco Machinery Spare Parts Co. Ltd Shanghai201206 China Shanghai Key Laboratory of High Temperature Materials and Precision Forming Shanghai Jiao Tong University Shanghai200240 China School of Materials and Energy Engineering Guizhou Institute of Technology Guizhou Guiyang550002 China

The poor thermal conductivity of Super Invar alloy (Fe-32Ni-4Co) further enhances the intrinsic building-height-dependent heat accumulation during its laser powder bed fusion (LPBF) process, resulting in its non-negligible microstructural inhomogeneity and significant property variation. In this paper, a detailed study for the effect of heat accumulation on microstructures, and thermal, mechanical and magnetic properties within a 10 × 10 × 100 mm3 vertically-built Super Invar alloy bar sample was conducted. Overall, LPBF fabricated Super Invar alloy exhibits considerably high degree of deformation and suffers very similar building-height-dependent thermal histories to the typical annealing process. The Curie temperature and Vickers hardness show a negative correlation with the lattice constant but a positive correlation with compressive residual stresses within this LPBF-manufactured Super Invar alloy bar. The vertically-measured coercivity is negatively correlated with the columnar grain size on the side surfaces, notwithstanding the pore-defect-induced coercivity enhancement within first-built layers. The segment of the bar located at a height of 50–75 mm exhibits relatively high bending degrees of magnetic domains, resulting in an extremely low coefficient of thermal expansion (CTE). In contrast, the 75–100 mm segment shows slightly higher CTE values compared to the 0–25 mm and 25–50 mm segments. The first-built segment of the Super Invar alloy bar sample contains coarse grains and significant small pores due to poor melting. This issue gradually diminishes as sufficient heat accumulates. As the building height increases further, a noticeable decline in dislocation density is observed without any change in grain size, indicating the occurrence of recovery at the building height of 30–40 mm. This recovery process causes a decrease in the Curie temperature and a reduction in hardness. Fine columnar grains can be achieved through heat accumulation processing, sugges

关键词： Curie temperature

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Designing Rules of Laser-Clad high-Entropy Alloy Coatings with Simple Solid Solution Phases

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Acta Metallurgica Sinica(English Letters) 2020年第8期33卷 1064-1076页

作者： Yongfei Juan Jiao Zhang Yongbing Dai Qing Dong Yanfeng Han Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai 200240China

The criteria of process parameters(μ≤4),atomic size difference(ε≤5.8,δ≤11 andα≤2),thermodynamic(-14.5≤△Hmix≤6.5 andΩ≥1.8)in the prediction of the phase stability for laser-clad high-entropy alloy coatings are studied in ***,the criteria of valence electron concentration(VEC)applied to distinguish the stability of different solid solution phases are as follows:VEC<7.65 for simple BCC,VEC≥7.65 for simple face-centered cubic(FCC),7.14high-entropy alloy coatings quite *** other modified criteria(δ,α,△Hmix,Ω,VEC)are proved to be different from those of the high-entropy alloys synthesized by the traditional casting and smelting processes.

关键词： high-entropy alloys Laser cladding Phase stability Criteria

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