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SSRN 2024年

作者： Zhu, Xiangjian Niu, Mengchao Liu, Shan Yu, Yanan Han, Luyi Zhao, Guoqun Wang, Guangchun State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Shandong Jinan250061 China Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University Shandong Jinan250061 China Department of Mechanical Engineering Research Institute for Advanced Manufacturing The Hong Kong Polytechnic University Hong Kong The Hong Kong Polytechnic University Shenzhen Research Institute Shenzhen518057 China Hebei Key Laboratory of Material Near-net Forming Technology Hebei University of Science and Technology Hebei Shijiazhuang050000 China

A method is proposed to enhance the thermal stability of laser-powder bed fusion fabricated (L-PBFed) alloys by incorporating Al element segregation through in-situ alloying. The high entropy alloy (HEA) with Al segregation was prepared through in-situ alloying of mixed powders of AlSi10Mg and FeCoCrNi, and the enhanced thermal stability of the grain boundary (GB) and dislocation in high-temperature annealing at 1000 °C and 1200 °C is verified and studied. Experimental characterization and molecular dynamics (MD) simulations revealed that the introduced Al segregation exists in two forms of B2/BCC phases, one in banded shape in the FCC matrix and the other as particles at GBs. At elevated temperatures, short-range uphill diffusion occurs within the banded B2/BCC phase, resulting in the formation of dispersed or mesh-like B2/BCC phases of higher Al and Ni content, along with the generation of dislocations. Additionally, long-range diffusion of Al atoms, originating from the aggregated region of banded B2/BCC, travels to the matrix, utilizing GBs as rapid channels. This diffusion stabilizes GBs by reducing their cohesive energy and maintaining the nailing effect of the B2/BCC phase at GBs. Consequently, the mechanical property exhibits remarkable resistance to softening compared to the traditional L-PBFed alloys. This study demonstrates that element segregation introduced by in-situ alloying serves as an effective approach to enhance the thermal stability of L-PBFed alloys. Furthermore, the proposed theory of sustained phase transitions offers insights into understanding the transitions of heterogeneous alloys fabricated through in-situ alloying at elevated temperatures. © 2024, The Authors. All rights reserved.

关键词： Molecular dynamics

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Overcoming the strength-ductility trade-off by tailoring grain-boundary metastable Si-containing phase in β-type titanium alloy

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Journal of materials Science & technology 2021年第9期68卷 112-123页

作者： X.Luo L.H.Liu C.Yang H.Z Lu H.W.Ma Z.Wang D.D.Li L.C.Zhang Y.Y.Li National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou510640China State Key Laboratory of Materials Processing and Die&Mould Technology Huazhong University of Science and TechnologyWuhan430074China Key Laboratory of Automobile Materials of MOE Department of Materials ScienceJilin UniversityChangchun130012China School of Engineering Edith Cowan University270Joondalup DriveJoondalupPerthWA 6027Australia

It is well accepted that grain-boundary phases in metallic alloys greatly deteriorate the mechanical *** our work,we report on a novel strategy to prepare high strength-ductility β-type(Ti69.71 Nb23.72Zr4.83Ta1.74)97Si3(at.%)(TNZTS) alloys by tailoring grain-boundary metastable Si-containing ***,the thin shell-shaped metastable S1 phase surrounding the columnar β-Ti grain was intercepted successfully via nonequilibrium rapid solidification achieved by selective laser melting(SLM).Subsequently,the thin shell-shaped metastable(Ti,Nb,Zr)5 Si3(called S1) phase was transformed into globular(Ti,Nb,Zr)2 Si(called S2) phase by the solution heat ***,the globular S2 phases reinforced TNZTS alloy exhibits ultrahigh yield strength of 978 MPa,ultimate strength of 1010 MPa and large elongation of 10.4 %,overcoming the strength-ductility trade-off of TNZTS alloys by various ***,the reported yield strength herein is 55 % higher than that of conventionally forged TNZT *** analysis indicates the globularization process of the metastable S1 phase is controlled by the model of termination *** quantitative analysis on strengthening mechanism demonstrates that the increase in yield strength of the heat-treated alloys is mainly ascribed to the strengthening of the precipitated silicide and the dislocations induced by high cooling *** obtained results provide some basis guidelines for designing and fabricating β-titanium alloys with excellent mechanical properties,and pave the way for biomedical application of TNZTS alloy by SLM.

关键词： Selective laser melting βtitanium alloys Heat treatment

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Shear bands of as-cast and semi-solid Ti_(48)Zr_(27)Cu_(6)Nb_(5)Be_(14)bulk metallic glass matrix composites

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China Foundry 2021年第1期18卷 75-82页

作者： Xin-hua Huang Lin-hao Zhu Hong-min Guo Hua-lan Jin Xiang-jie Yang School of Mechanical and Electrical Engineering Nanchang UniversityNanchang330031China Key Laboratory of Near Net Forming in Jiangxi Province Nanchang UniversityNanchang330031China School of Material Science and Engineering Nanchang UniversityNanchang330031China Hunan Province Special Equipment Inspection and Research Institute Changsha410117China

The as-cast Ti_(48)Zr_(27)Cu_(6)Nb_(5)Be_(14)bulk metallic glass matrix composites(BMGMCs)were fabricated using a copper mold suction casting ***,the semi-solid BMGMC samples were obtained following an isothermal treatment(heating at 900°C for 10 min,then cooling with water).The microstructure and compression property were investigated by scanning electronic microscopy(SEM)and universal mechanical *** a result of the isothermal treatment,the crystal shapes change from fine,granular,and dendritic to spherical or vermicular,and the average crystal size of the as-cast and semi-solid samples is 2.2μm and 18.1μm,*** plasticity increases from 5.31%in the as-cast to 10.23%in the semi-solid samples,with an increase of 92.66%.The shear bands from different areas of the side surfaces of as-cast and semisolid compression fracture samples were *** characteristic changes of multiplicity,bend,branch and intersection of shear bands in different areas indicate that the deformation of as-cast and semi-solid samples is non-uniform during *** is found that poor plasticity of the as-cast samples or good plasticity of the semi-solid samples are reflected by characteristics of the shear *** semi-solid isothermal treatment improves the plasticity by forming large crystals which can block the expansion of shear bands and promote the multiplicity of shear bands.

关键词： shear bands Ti_(48)Zr_(27)Cu_(6)Nb_(5)Be_(14) as-cast semi-solid plasticity

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Pulsing-Induced Healing of a Surface Crack of a Nickel-Based Alloy

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SSRN 2024年

作者： Wang, Qian Quan, Mingming Tan, Zhen Liu, Ming Wang, Dianlong Yang, Xiao Liu, Ying Mao, Yaning Liang, Zhimin Yang, Fuqian Wang, Liwei School of Material Science and Engineering Hebei University of Science and Technology Shijiazhuang050018 China Hebei Key Laboratory of Material Near-Net Forming Technology Shijiazhuang050018 China School of Mechanical Engineering and Automation Fuzhou University Fuzhou350108 China HBIS Group Materials Institute HBIS Group Hebei Shijiazhuang050023 China Materials Program Department of Chemical and Materials Engineering University of Kentucky LexingtonKY40506 United States School of Material Science and Engineering Australia

In this work, we demonstrate the feasibility of applying electric pulses to heal surface cracks on Ni-based GH4169 alloy under compressive load. There exists an incubation time for the onset of the healing of a crack, which is associated with local temperature at the crack tip. The crack size decreases with increasing the pulsing time at a constant healing rate prior to complete healing of the crack. Increasing compressive load accelerates the healing process. The electric pulsing leads to the formation of an influential zone surrounding the crack with the finest grain sizes in the healed crack and the coarsest grain sizes away from the influential zone. The indentation hardness increases with the increase the distance to the crack tip of the healed crack. A model of viscous flow in the crack channel is proposed for the crack healing. The resultant force on the crack faces due to the crack healing increases with the increase of the healing time and the decrease of the crack width. © 2024, The Authors. All rights reserved.

关键词： Crack tips

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Nano-amorphous–crystalline dual-phase design of Al_(80)Li_(5)Mg_(5)Zn_(5)Cu_(5)multicomponent alloy

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Science China materials 2022年第6期65卷 1671-1678页

作者： Hongzhen Li Chao Yang Jianan Fu Weisi Cai Yuqiang Yan Jiang Ma Shenzhen Key Laboratory of High Performance Nontraditional Manufacturing College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China Songshan Lake Materials Laboratory Dongguan 523808China

The design of metallic materials with high strength,high ductility,and high thermal stability has always been a long-sought goal for the materials science ***,the trade-off between strength and ductility remains a ***,we proposed a new strategy to design and fabricate bulk amorphous-crystalline dual-phase superior alloys out of the Al_(80)Li_(5)Mg_(5)Zn_(5)Cu_(5)multicomponent *** nano-amorphous phase revealed unexpected thermal stability during fabrication and mechanical testing above the crystallization *** true fracture strength of the Al_(80)Li_(5)Mg_(5)Zn_(5)Cu_(5)nano-amorphous-crystal dual-phase multicomponent alloy was increased from 528 to 657 MPa,and the true strain was increased from 18%to 48%.In addition,the alloy yielded a strength 1.5 times higher than that of the commonly used high-strength aluminum alloys at 250℃.This strategy provided a new approach and concept for the design of high-performance alloys to ensure strength-plasticity balance.

关键词： amorphous alloys nanocrystalline alloys multicomponent alloy high-performance alloys

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Microstructural Evolution and Carbides Precipitation Behavior and Their Effects on Mechanical Property of Nb-Ti Microalloyed Fb590 Steel

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SSRN 2024年

作者： Zheng, Yaxu Chu, Shaokang Yang, Qin Lin, Yu Zhu, Liguang Li, Yongliang Guo, Zhihong Zhang, Di Cao, Ruifang Feng, Jie Wang, Bo School of Material Science and Engineering Hebei Short Process Steel Making Technology Innovation Center Hebei Key Laboratory of Material Near-Net Forming Technology Hebei University of Science and Technology Shijiazhuang050018 China QuesTek Innovations EvanstonIL United States College of Materials Science and Engineering Chongqing University Chongqing400045 China Rolling operation department Beijing Shougang Co. LTD. Tangshan064404 China Hebei University of Science and Technology China

Ferrite-bainite dual phase steels have been widely used in automobile manufacturing industry due to their high strength and excellent hole expansion performance. In this study, the effects of coiling temperature on mechanical properties and hole expansion performance of low carbon Nb-Ti micro-alloyed FB590 ferrite-bainite steel have been studied. Additionally,, the microstructure evolution and carbide precipitation behavior during hot rolling and coiling processes have been investigated. The influence mechanism of microstructures and carbides on both mechanical properties and hole expansion performance has also been discussed. The results suggest that the fraction of the retained austenite and the martensite decreases gradually with increasing coiling temperatures from 450℃ to 500℃. The main reason for the formation of martensite and retained austenite in steel 1# coiled at 450℃ is that the coiling temperature is in the martensitic transformation range. Increasing the coiling temperature to 500℃ which is above the Ms leads to ferritic and bainitic structure. The carbides precipitation behavior has been studied by TEM, thermodynamic and kinetics calculation. The results show that the size of the carbides increases with increasing coiling temperatures from 450°C to 500°C. Most of the large size carbides above 100 nm with high percent of Ti are the undissolved particles in austenite during slab heating. The medium size particles between 10 nm and 100 nm precipitate during hot rolling. The small size carbides below 10 nm with high percent of Nb precipitate during coiling. The strength of the steel is effectively increased by the fine carbides and martensite formed at low coiling temperature of 450°C. However, the fine carbides, martensite and residual austenite are bad for plasticity and hole expansion performance. Raising the coiling temperature of FB590 steel from 450℃ to 500°C can effectively reduce the content of martensite and retained austenite in the steel. Altho

关键词： Microalloying

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Microstructure and microhardness of a novel TiZrAlV alloy by laser gas nitriding at different laser powers

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Rare Metals 2020年第3期39卷 270-278页

作者： Zhi-Hao Feng Xin-Yang Sun Peng-Biao Han Hang Fu Hui-Cong Dong Shun Guo Ru Su Jian-Hui Li Hebei Key Laboratory of Material Near-net Forming Technology Hebei University of Science and TechnologyShijiazhuang050000China Hebei Engineering Laboratory of Aviation Lightweight Composite Materials and Processing Technology Hebei University of Science and TechnologyShijiazhuang050000China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004China School of Materials Science and Engineering Jiangsu UniversityZhenjiang212013China

The Ti-20Zr-6.5Al-4V(T20Z,wt%)alloy surface was treated by the process of laser surface *** evolution of microstructures and microhardness has been investigated by changing the laser power parameter from 120 to 240 *** laser-treated T20Z samples show two regions with distinctly different microstructural features,as compared with the untreated substrate:dense TiN dendrites and(α+β)-Ti(remelting zone,RMZ),nanoscaleαlaths doped with part of p phase(heat-affected zone,HAZ).The formation of TiN dendrites can be analyzed by a series of complex reactions during the process of melting and *** increase in laser power results in the increase in content of TiN dendrite which is mainly due to the increase in energy *** HAZ,the self-quenching effect leads to the formation of nanoscale a laths and the residue ofβ*** profile of different regions was measured from the surface to the interior,and the highest microhardness was obtained(~HV 916.8)in the RMZ,as the laser power was set to 240 *** the present study,we explained various microstructural characteristics induced by laser surface nitriding treatment.

关键词： TiZrAlV alloy Laser surface nitriding Microstructure TiN dendrites Microhardness

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Research on the Strengthening Mechanism of Nb-Ti Microalloyed Ultra Low Carbon If Steel

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SSRN 2024年

作者： Zheng, Yaxu Wang, Kun Yang, Qin Lin, Yu Zhu, Liguang Wu, Xiaoyan Han, Baochen Wang, Bo Zhang, Di Feng, Jie Cao, Ruifang School of Material Science and Engineering Hebei Short Process Steel Making Technology Innovation Center Hebei Key Laboratory of Material Near-Net Forming Technology Hebei University of Science and Technology Shijiazhuang050018 China QuesTek Innovations EvanstonIL United States College of Materials Science and Engineering Chongqing University Chongqing400045 China Rolling Operation Department Beijing Shougang Co. LTD. Tangshan064404 China

The microstructure evolution and carbides precipitation behavior during the hot rolling, cold rolling and annealing processes have been studied. The results indicates that the addition of Nb into Ti bearing IF steel promotes the recrystallization at 900 ℃ and obtains fine recrystallized grains. Based on the fine and uniform original structure, Nb-Ti microalloyed steel obtains fine structure after cold rolling and annealing. The study results of the carbides precipitation behavior suggests that the TiN precipitates at high temperature above 1100 ℃, and a large amount of (Nb,Ti)C and TiC precipitate at about 900 ℃ in Nb-Ti and Ti bearing steels, respectively. There is no significantly difference between the amount of carbides in hot deformed steels at 900 ℃ and the hot rolled plates, which indicates that the carbides mainly precipitate during the hot rolling process due to the ultra low carbon and nitrogen content in the steel. However, there is few carbides precipitate during the coiling process at 600 ℃. The thermodynamic and kinetic calculation results are consistent with the TEM observation results. In Nb-Ti containing steel, the solid solution of Nb and Ti elements are significantly reduced due to the large amount precipitation of (Nb,Ti)C during the final rolling process, which effectively promotes the recrystallization of austenite. Therefore, the grains of hot-rolled, cold-rolled, and annealed strips are refined, and the fine-grained strengthening effect is improved. Finally, the strength of Nb-Ti containing steel is higher than that of Ti containing steel. © 2024, The Authors. All rights reserved.

关键词： Microalloying

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Development of Predictive Maintenance System for Nuclear Power Turbine Unit

Development of Predictive Maintenance System for Nuclear Pow...

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International Conference on Artificial Intelligence and Computer Information technology (AICIT)

作者： Junhao Tang Dongdong You Fenglei Li Yong Cheng Guangdong Key Laboratory for Advanced Metallic Materials Processing National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials Guangdong China Beijing Qingtai Data Technology Co. Ltd Beijing China

The safe operation of nuclear power plants is the most concerned issue in the nuclear power industry. Intelligent early warning and predictive maintenance of mechanical equipment such as steam turbines can effectively prevent nuclear power plant safety accidents and reduce maintenance costs. This paper will introduce the architecture and process of predictive maintenance system and apply it to nuclear power steam turbine units. The developed predictive maintenance system of nuclear power steam turbine units is equipped with LSTM-Bayes signal anomaly recognition method, benchmarking other manufacturers' systems, and improving many indicators. For example, new early warning parameters such as abnormal probability, remaining useful life and characteristic signals are added to help maintenance, making it more intelligent. It has been verified that the input of the system reduces the failure rate of mechanical equipment, saves maintenance costs, can effectively ensure safe operation, improve productivity and reduce costs.

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Preparation of Nano Al 3 Ti-Tib 2 -Aln-Tin/Al Inoculant Ribbons And its Effect On Microstructures and Properties Of Alznmgcu Alloys

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SSRN 2023年

作者： Wang, Qian Zhao, Jinman Cui, Chunxiang Wu, Dayong He, Peng Ma, Haikun Kang, Jie Dong, Huicong Su, Ru Hebei Key Laboratory of Material Near-Net Forming Technology School of Materials Science and Engineering Hebei University of Science and Technology Shijiazhuang050018 China Key Lab. for New Type of Functional Materials in Hebei Province School of Materials science and Engineering Hebei University of Technology Tianjin300130 China China International Engineering Consulting Corporation Beijing100048 China

The nano Al3Ti-TiB2-AlN-TiN/Al inoculant ribbons which contain a large number of evenly distributed nano particles, such as Al3Ti (size about 300 nm),TiB2 (size about 100 nm), AlN (size about 150 nm) and TiN (size about 200 nm) were prepared by vacuum rapid quenching furnace to refine the AlZnMgCu alloys. The nano Al3Ti-TiB2-AlN-TiN/Al inoculant ribbons showed excellent inoculant effect, which modified the dendrite crystals to equiaxed crystals and refined the grains from 122 ± 4 μm to 36 ± 5 μm by addition of 0.3 wt% nano Al3Ti-TiB2-AlN-TiN/Al inoculant ribbons. In addition to nano Al3Ti and TiB2 particles, nano AlN and TiN particles also have a certain orientation relationship with α-Al, which suggest that these particles possess nucleation potency to α-Al. After inoculated by 0.3% nano Al3Ti-TiB2-AlN-TiN/Al inoculant ribbons, the ultimate tensile strength, yield strength, and microhardnessof the AlZnMgCu alloys increased from 246 MPa, 79 MPa, and 112 HV to 319 MPa, 100 MPa, and 136 HV, increased by 29.7%, 26.6% and 21.4%, respectively. © 2023, The Authors. All rights reserved.

关键词： Nanoparticles

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