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Journal of materials Science & Technology 2023年第23期154卷 43-53页

作者： Lin Wang Zhipeng Long Long Hou Song Yan Baode Sun Xi Li Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming Shanghai Jiao Tong University Shanghai 200240 China State key laboratory of advanced Special Steels Shanghai University Shanghai 200072 China

The effects of a high magnetic field on the evolution of the single-phase interface and the liquid-solid interface energy in Al-Cu alloy were investigated experimentally.It is found that the application of the magnetic field has a significant promotion effect on the migration of liquid droplets,accelerating the formation of the single-phase interface.This should be attributed to the thermoelectric(TE)magnetic convection in the droplets which has enhanced the diffusion and increased the migration speed of liquid droplets.Further,the effect of the high magnetic field on the solid-liquid interface energy is analyzed by an improved grain boundary groove(GBG)method.The average solid-liquid interface energy of theα-Al/Al-Cu and Al2Cu/Al-Cu systems increases and decreases with the increase of the magnetic field,respectively.The above experiment results are well explained based on the formation and interaction of the magnetic dipole at the solid-liquid interface.Moreover,experimental results reveal that the magnetic-field-induced interface energy increases and decreases the nucleation undercooling of the Al-30wt.%Cu alloy and Al-35wt.%Cu alloy,respectively.By studying the effect of the magnetic-field-induced interface energy on the nucleation undercooling,the understanding of the interface energy-induced nucleation undercooling deepens.

关键词： high magnetic field Interface energy Nucleation undercooling Grain boundary groove

Dislocation glide and mechanical twinning in a ductile VNbTi medium entropy alloy

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Journal of materials Science & Technology 2022年第15期110卷 210-215页

作者： Mingxu Wu Shubin Wang Fei Xiao Guoliang Zhu Chao Yang Da Shu Baode Sun Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming and State key lab of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

An equiatomic VNbTi medium-entropy alloy with outstanding tensile properties and unique deformation behavior is reported.The screw dislocation glide,deformation twinning,and dislocation accumulation induced kink bands are identified as three deformation mechanisms that contribute to a large elongation above 20%.The{112}twins are activated at the beginning of the yield stage accompanied by sudden stress-drop and pronounced acoustic emission.Dislocations dominate subsequent tensile deformation,and the prevalent multiplanar dislocation slip promotes the formation of complex dislocation configurations(e.g.,debris,dipoles,and loops)and dense dislocation networks.The twin bands and kink bands can further impede the dislocation motion meanwhile effectively alleviate stress concentration.The synergistic activation of these deformation mechanisms provides new opportunities to design ductile refractory medium-and high-entropy alloys.

关键词： Medium-entropy alloy Mechanical twinning Screw dislocation Multiplanar slip Tensile deformation

A review on prediction of casting defects in steel ingots:from macrosegregation to multi-defect model

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Journal of Iron and Steel Research(International) 2022年第12期29卷 1901-1914页

作者： Jun Li Xiao-wei Xu Neng Ren Ming-xu Xia Jian-guo Li School of materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China shanghai key laboratory of advanced high-temperature materials and precision forming Shanghai 200240China

Due to the nature of the solute redistribution,the reduction in the solidification rate with time in a square root relationship,and the multiphase melt flow during the solidification,casting defects such as macrosegregation,shrinkage cavity,and porosity will inevitably occur in the steel ingot and intensify with the increase in ingot size.These defects directly affect the performance of the final product and severely restrict the choice of subsequent thermal processing methods and process windows.Therefore,the solidification defects including macrosegregation,shrinkage/porosity,and inclusions encountered in the preparation of large steel ingots and their formation mechanisms were reviewed.The development progress and the latest development of the macrosegregation model for steel ingots were introduced in detail,especially the latest progress in the coupling prediction of macrosegregation and shrinkage as well as macrosegregation and inclusions.Some methods to reduce macrosegregation of ingots were discussed as well.Finally,a new casting method called layered casting was introduced in detail.This method can effectively improve the uniformity of the macrostructure and reduce the macrosegregation of the large ingots and therefore is a promising method for preparing large ingots with high homogeneity.

关键词： Steel ingot Macrosegregation Numerical modeling Multiphase model Solidification defect

Atomic scale visualizations of low-angle grain boundary mediated plasticity by coupled dislocation climb and glide in nanoporous gold

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Nano Research 2023年第2期16卷 2622-2629页

作者： Shufen Chu Junnan Jiang Xiaoran Zhao Baode Sun Pan Liu shanghai key laboratory of advanced high-temperature materials and precision forming State Key Laboratory of Metal Matrix CompositesSchool of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Grain boundaries(GBs),as a prevalent structural characteristic,play a crucial role in the deformation of nanoporous metals with nanosized grains and ligaments.However,the fundamental understanding of GB-mediated deformation is still lacking because the plastic behavior of discrete ligaments involving GBs remains to be unknown.Here,we report atomic scale visualizations of coupled GB dislocation climb and glide in nanoporous gold ligaments with low-angle GBs via in situ tensile straining inside a Cs-corrected transmission electron microscope.The zig-zag motion paths of GB dislocations are precisely determined by real-time tracking of the movements of dislocation cores.The concurrent climb and glide of the dislocation arrays are confined to a narrow GB region,greatly enhancing GB diffusion in the bicrystal ligament.Our findings of coupled dislocation climb and glide shine a light on the room-temperature deformation of nanoporous metals and provide a time-dependent atomic-level physical image for GB engineering.

关键词： nanoporous gold dislocation climb dislocation glide low-angle grain boundaries

Effects of V addition on the mechanical properties at elevated temperatures in a γ”-strengthened NiCoCr-based multi-component alloy

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Journal of materials Science & Technology 2022年第12期107卷 290-300页

作者： Yunwei Pan Anping Dong Yang Zhou Dafan Du Donghong Wang Guoliang Zhu Baode Sun Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China State key lab of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China

Ni Co Cr-based multi-component alloys have drawn much attention due to their exceptional ductility and strain hardening capacity.However,insufficient strength-ductility synergy of NiCoCr alloy has always been an issue that prevents it from extensive applications.According to our previous research,the precipitation ofγ”phase can significantly improve the strength-ductility synergy of this alloy system at room temperature.In this study,the effects of V addition onγ”phase stability and high-temperature mechanical properties have been explicitly investigated.The results indicate that V addition can stabilize the metastableγ”phase in this alloy system and prevent it from transforming into a stableδphase at grain boundaries upon 650℃aging,resulting in improved mechanical properties at elevated temperatures.The specific strength ofγ”-strengthened multi-component NiCoCr-based alloy can reach up to 86.2 MPa gcmat 650℃,which is higher than those of Ni-based superalloys,IN 939 and Waspaloy.This work provides theoretical guidance for the novel design of γ”-strengthened alloy for high-temperature applications.

关键词： Multi-component alloys CALPHAD γ”phase Microstructural evolution high-temperature mechanical properties

Influence Factors of Aluminum–Slag Interfacial Reaction Under Electric Field

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Acta Metallurgica Sinica(English Letters) 2017年第8期30卷 753-761页

作者： Xin-Yu Lv An-Ping Dong Jun Wang Da Shu Bao-De Sun shanghai key laboratory of advanced high-temperature materials and precision forming Shanghai Jiao TongUniversity Shanghai 200240 China

The interfacial reaction between aluminum melt and molten slag under an electric field plays a significant role in aluminum electro-slag refining. Here we studied this interracial reaction within 680 and 820 ℃ under an electric field between 0 and 9 V. The evolution of aluminum composition was analyzed by inductively coupled plasma atomic emission spectroscopy. The dominant factor during the interfacial reaction was identified through orthogonal experiments, in which the slag-to-aluminum mass ratio, initial silicon concentration, electric voltage, reaction time, and temperature were selected as the influence factors. The greatest influence factor on the interracial reaction was found to be the reaction time. Also, single-factor experiments revealed that the reaction kinetic processes largely obeyed an irreversible kinetic model, and the silicon removal efficiency was enhanced by increasing the voltage and slag/metal ratio.

关键词： Molten salts Interfacial reaction Silicon Electric field Aluminum Kinetic model

Formation mechanism of ring-like segregation and structure during directional solidification under axial static magnetic field

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Journal of materials Science & Technology 2022年第4期99卷 48-54页

作者： Qingdong Zhong Huaiyu Zhong Hongbo Han Mingyong Shu Long Hou Yanyan Zhu Xi Li Panzhihua University Panzhihua 417000China State key laboratory of advanced Special Steels Shanghai UniversityShanghai 200072China Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai 200240China

The effect of the axial static magnetic field on the macro-segregation and structure in the Al-Cu and NiMn-Ga alloys during directional solidification is investigated experimentally and numerically.It is found that the ring-like segregation and structure in the above-mentioned two alloys form during directional solidification at a certain growth speed under a moderate magnetic field.For the Al-Cu and Ni-Mn-Ga alloys,the moderate values of the magnetic field under which the ring-like structure forms are about 0.5 T and 1.0 T at respective growth speed of 10μm/s and 5μm/s.Further,the distributions of the flow and solute in the Al-Cu alloy during directional solidification under the axial static magnetic field is numerically simulated.Numerical results reveal that the rotary thermoelectric(TE)magnetic convection forms in the mushy zone during directional solidification under an axial magnetic field.This flow will induce the formation of the ring-like macro-segregation and structure.Changes in structures under the magnetic field in the experimental results are in good agreement with the distributions of the TE magnetic convection and solute in the numerical results.Therefore,the formation of the ring-like structure and segregation under the magnetic field should be attributed to the solute redistribution induced by the TE magnetic convection.

关键词： Ring-like segregation and structure Magnetic field Directional solidification

Premature failure induced by non-equilibrium grain-boundary tantalum segregation in air-plasma sprayed ZrO_(2)-YO_(1.5)-TaO_(2.5)thermal barrier coatings

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International Journal of Minerals,Metallurgy and materials 2022年第12期29卷 2189-2200页

作者： Yao Yao Di Wu Xiaofeng Zhao Fan Yang shanghai key laboratory of advanced high temperature materials and precision forming Shanghai Jiao Tong UniversityShanghai 200240China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

ZrO_(2)-YO_(1.5)-TaO_(2.5)(ZYTO)is a promising top-coat material for thermal barrier coatings(TBCs).The bulk properties of ZYTO have been reported by several studies,but its performances as TBCs are less-well understood.In this work,ZYTO TBCs were prepared by air plasma spraying(APS)and their thermal cycling performances were investigated at 1150℃.Despite of the good bulk properties,APS ZYTO TBCs present an extremely short thermal fatigue life.This is attributed to the non-equilibrium grain-boundary segregation of TaO_(2.5) induced by limited solubility and rapid quenching during APS process,resulting in a tetragonal(t)to cubic(c)and metastable-tetragonal(tm)phase transformation in ZYTO TBCs.The volume shrinkage(~0.74vol%)of phase transformation leads to many cracks at the c/tm phase boundaries after deposition.On the other hand,the formation of cubic phase with massive grain-boundary Ta segregation induces a large intergranular embrittlement and a weak bonding strength(~5.3 MPa),resulting in the premature failure of the ZYTO TBCs.

关键词： thermal barrier coatings air plasma spray tantalum segregation phase transformation

Corrosion of Duplex Stainless Steel Manufactured by Laser Powder Bed Fusion: A Critical Review

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Acta Metallurgica Sinica(English Letters) 2024年第4期37卷 587-606页

作者： Yiqi Zhou Decheng Kong Ruixue Li Xing He Chaofang Dong Beijing advanced Innovation Center for materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083China shanghai key laboratory of advanced high-temperature materials and precision forming School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai200240China

Laser powder bed fusion (LPBF) is a commonly used additive manufacturing (AM) method for efficiently producing intricate geometric components. This investigation examines factors such as pores, cellular structure, grain size, and inclusions from the manufacturing process that contribute to the corrosion resistance of LPBF DSS. Furthermore, the as-built LPBF duplex stainless steel (DSS) is primarily ferrite due to the rapid cooling process. Therefore, the transformation of ferrite to austenite after various heat treatments in LPBF DSS and its corresponding corrosion resistance are presented. Additionally, a new mixed powder method is proposed to increase the austenite content in the as-built LPBF DSS. This review also focuses on the passivation capability and pitting corrosion performance in LPBF and conventional DSS. This article summarizes the variations in microstructure between as-built and heat-treated LPBF DSS, with their impacts on corrosion resistance, offering insights for manufacturing highly corrosion-resistant LPBF DSS.

关键词： Laser powder bed fusion Duplex stainless steel Microstructure Heat treatment Passivation Pitting corrosion

Accelerating materials discovery using machine learning

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Journal of materials Science & Technology 2021年第20期79卷 178-190页

作者： Yongfei Juan Yongbing Dai Yang Yang Jiao Zhang Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai200240China Department of Computer Science and Engineering Shanghai Jiao Tong UniversityShanghai200240China

The discovery of new materials is one of the driving forces to promote the development of modern society and technology innovation,the traditional materials research mainly depended on the trial-and-error method,which is time-consuming and laborious.Recently,machine learning(ML)methods have made great progress in the researches of materials science with the arrival of the big-data era,which gives a deep revolution in human society and advance science greatly.However,there exist few systematic generalization and summaries about the applications of ML methods in materials science.In this review,we first provide a brief account of the progress of researches on materials science with ML employed,the main ideas and basic procedures of this method are emphatically introduced.Then the algorithms of ML which were frequently used in the researches of materials science are classified and compared.Finally,the recent meaningful applications of ML in metal materials,battery materials,photovoltaic materials and metallic glass are reviewed.

关键词： materials discovery materials design materials properties prediction Machine learning Data-driven