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Understanding formation of Mg-depletion zones in Al-Mg alloys under high pressure torsion

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Journal of Materials Science & Technology 2019年第5期35卷 858-864页

作者： Jing Xue Shenbao Jin Xianghai An Xiaozhou Liao Jiehua Li gang sha Herbert Gleiter Institute of Nanoscience School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China School of Aerospace Mechanical and Mechatronic Engineering The University of Sydney Sydney NSW 2006 Australia Institute of Casting Research Montanuniversitat Leoben A-8700 Leoben Austria

Redistribution of elements may take place in alloys during severe plastic deformation, which significantly alters the mechanical properties of the alloys. Therefore, comprehensive knowledge about deformationinduced redistribution of elements has to be established. In the present paper, the distribution of Mg in an Al-Mg alloy processed by high pressure torsion was examined using atom probe tomography(APT).With crystallographic information extracted by APT data analysis, this research reveals that the movement of dislocations plays an important role in the formation of Mg-depletion zones in the deformed microstructure.

关键词： High-pressure torsion Atom probe tomography Aluminum alloys Grain boundary diffusion Dislocation

Origins of high ductility exhibited by an extruded magnesium alloy Mg-1.8Zn-0.2Ca:Experiments and crystal plasticity modeling

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Journal of Materials Science & Technology 2021年第25期84卷 27-42页

作者： Jie Wang Gaoming Zhu Leyun Wang Evgenii Vasilev Jun-Sang Park gang sha Xiaoqin Zeng Marko Knezevic National Engineering Research Center of Light Alloy Net Forming Shanghai Jiao Tong UniversityShanghai200240China Department of Mechanical Engineering University of New HampshireDurhamNH03824USA Advanced Photon Source Argonne National LaboratoryLemontIL60439USA School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing210094China State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai200240China

Low ductility and strength are major bottlenecks against Mg alloys’wide *** this work,we systematically design the composition and fabrication process for a low-alloyed Mg-Zn-Ca alloy,showing that it can be extruded at low temperatures(~250℃)and high speeds(~2 mm/s).After the extrusion,this alloy exhibits a substantially weakened basal texture,relatively small grain size,very high tensile elongation(~30%),and good *** origin of the considerably improved ductility was studied using a combination of three-dimensional atom probe tomography(3D-APT),transmission electron microscopy(TEM),electron backscattered diffraction(EBSD)in conjunction with surface slip trace analysis,in-situ synchrotron X-ray diffraction,and elasto-plastic self-consistent(EPSC)***-segregation of Zn and Ca atoms at a grain boundary is observed and associated with texture weakening and grain boundary mediated plasticity,both improving the *** basal slip and prismatic slip are identified as the dominant deformation systems in the alloy,the ratio between their slip resistances is substantially reduced relative to pure Mg and most other Mg alloys,significantly contributing to the improved ductility of the *** Mg-Zn-Ca alloy exhibiting excellent mechanical properties and low fabrication cost is a promising candidate for industrial productions.

关键词： Mg-Zn-Ca alloy Ductility Deformation mechanisms Crystal plasticity modeling Grain boundary mediated plasticity

Enhancement of strength-ductility balance of heavy Ti and Al alloyed FeCoNiCr high-entropy alloys via boron doping

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Journal of Materials Science & Technology 2021年第16期75卷 154-163页

作者： Yongliang Qi Tinghui Cao Hongxiang Zong Yake Wu Lin He Xiangdong Ding Feng Jiang Shenbao Jin gang sha Jun Sun State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'anShanxi 710049China School of Materials Science and Engineering Nanjing University of Science and TechnologyJiangsu210094China

As one of the most effective mechanisms,precipitation-hardening is widely used to strengthen high-entropy ***,heavy precipitation-hardened high-entropy alloys usually exhibit serious *** to effectively achieve ultra-high strength and maintain reliable ductility remains a ***,we report a study of doping extremely little boron to meet this *** found that adding of 30 ppm boron into the heavy Ti and Al alloyed FCC FeCoNiCr high-entropy,(FeCoNiCr)_(88) Ti_(6) Al_(6) HEA(at.%)which is strengthened mainly by both coarse BCC-based(Ni,Co)_(2) TiAl Heusler and fine L12-type FCC-based(Ni,Co)_(3) TiAl precipitates and shows ultrahigh strength but poor ductility,could significantly change the original microstructure and consequently improve mechanical performance,owing to the well-known effect of boron on reducing the energy of grain *** boron addition can(1)eliminate microcavities formed at Heusler precipitate-matrix interfaces;(2)suppress the formation and segregation of coarse BCC Heusler precipitates;(3)promote the formation of L12 *** changes of microstructure substantially improve the tensile ductility more than by~86%and retain comparable or even better ultimate tensile *** findings may provide a simple and costless solution to produce heavy precipitation-strengthened HEAs with ultrahigh strength and prevent accidental brittleness.

关键词： High-entropy alloy Precipitation strengthening Boron Ductility

Excellent strength-ductility combination of Cr_(26)Mn_(20)Fe_(20)Co20Ni_(14) high-entropy alloy at cryogenic temperatures

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Journal of Materials Science & Technology 2023年第23期154卷 166-177页

作者： Xuzhou Gao Wei Jiang Yiping Lu Zhigang Ding Jizi Liu Wei Liu gang sha Tongming Wang Tingju Li Isaac T.H.Chang Yonghao Zhao Nano and Heterogeneous Materials Center School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing 210094 China Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province) School of Materials Science and Engineering Dalian University of Technology Dalian 116024 China Herbert Gleiter Institute of Nanoscience Nanjing University of Science and Technology Nanjing 210094 China Metallurgy and Head of Liquid Metal Engineering (LiME) Doctoral Training Centre Brunel Centre for Advanced Solidification Technology (BCAST) Brunel University London Uxbridge UB8 3PH UK

In the present study,a face-centered cubic non-equiatomic Cr_(26)Mn_(20)Fe_(20)Co20Ni_(14) high-entropy alloy(HEA)with a low stacking fault energy of 17.6 mJ m^(−2) was prepared by vacuum induction melting,forging and annealing *** recrystallized sample is revealed to exhibit an excellent combination of strength and ductility over a wide temperature range of 4.2–293 *** decreasing temperature from 293 to 77 K,the ductility and ultimate tensile strength(UTS)gradually increase by 30% to 95% and 137% to 1020 MPa,*** the lowest temperature of 4.2 K,the ductility keeps 65% and the UTS increases by 200% to 1300 MPa,which exceed those published in the literature,including conventional 300 series stainless *** microstructural analyses of this alloy reveal a change of deformation mechanisms from dislocation slip and nano-twinning at 293 K to nano-phase transformation at 4.2 *** cooperation and competition of multiple nano-twinning and nano-phase transformation are responsible for the superior tensile properties at cryogenic *** study provides experimental evidence for potential cryogenic applications of HEAs.

关键词： High-entropy alloys Strength and ductility Cryogenic temperature Twinning Phase transformation

Space, Time, and the Creation of Universe

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Journal of Philosophy Study 2017年第2期7卷 66-74页

作者： Zhi gang sha Rulin Xiu Institute of Soul Healing and Enlightenment

The understanding about the creation of our universe is explored in many philosophies, natural sciences, religions, ideologies, traditions, and disciplines. Current natural science cannot answer this question at the fundamental level. In this work, we combine the ancient Chinese Tao wisdom about the creation with quantum physics. We propose that everything comes from the emptiness. Our universe is manifested from the emptiness through two pairs of duality measurements： space and time duality pair and inclusion and exclusion duality pair. From this understanding, we are able to derive one mathematic formula describing our universe. It also yields a new metaphysical approach to derive and interpret string theory as well as produce more testable predictions from string theory. This work gives a new way to understand and mathematically describe how our universe is created and evolved. It provides another way to comprehend the meaning and function of space and time. It indicates that our universe is manifested from the emptiness through human actions. Space and time is a pair of duality action and codes that help manifest our universe. It provides answer to an important philosophical question about whether and why we can understand and mathematically describe our universe.

关键词： space time creation of universe string theory Tao wisdom quantum physics measurement theory duality manifestation grand unification theory

A New Scientific Definition of Sickness and Healing

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Psychology Research 2018年第9期8卷 478-481页

作者： Zhi gang sha Rulin Xiu Institute of Soul Healing and Enlightenment Richmond Hill Canada Hawaii Theoretical Physics Research Center Hawaii USA

Derivation of Multiverse from Universal Wave Function Interpretation of String Theory

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Journal of Physical Science and Application 2017年第6期7卷 1-5页

作者： Zhi gang sha Rulin Xiu Institute of Soul Healing and Enlightenment 30 Wertheim Court Unit 27D Richmond Hill Ontario L4B 1B9 Canada Hawaii Theoretical Physics Research Center 16-266 E. Kipimana St Keaau HI 96749 USA

The multiverse is a hypothesis created to solve certain problems in cosmology. Currently, this scheme is still largely ad hoc, rather than derived from fundamental laws and principles. Because of this, the predictive power of this theory is rather limited. Furthermore, there are concerns that this theory will make it impossible to calculate some measured quantities, such as the masses of quarks and the electron. In this paper, we will show that a new development in string theory, the universal wave function interpretation of string theory, provides a way to derive the mathematical expression of the multiverse. We will demonstrate that the Weyl invariance existing in string theory indicates that our observed universe is a projection from a hologram. We will present how the laws of physics can be derived from this fact. Furthermore, we suggest it may also provide a way to calculate the masses of fundamental particles such as quarks and the electron.

关键词： String theory multiverse grand unification theory cosmology holographic universe universal wave function interpretation of string theory.

Development of the high-strength ductile ferritic alloys via regulating the intragranular and grain boundary precipitation of G-phase

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Journal of Materials Science & Technology 2023年第5期136卷 180-199页

作者： Mujin Yang Chao Huang Jiajia Han Haichen Wu Yilu Zhao Tao Yang Shenbao Jin Chenglei Wang Zhou Li Ruiying Shu Cuiping Wang Huanming Lu gang sha Xingjun Liu School of Materials Science and Engineering Harbin Institute of TechnologyShenzhen 518055China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China College of Materials and Fujian Provincial Key Laboratory of Materials Genome Xiamen UniversityXiamen 361005China Test Center Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Department of Materials Science and Engineering City University of Hong KongHong KongChina Department of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyShenzhen 150001China Institute of Materials Genome and Big Data Harbin Institute of TechnologyShenzhen 518055China

A typical G-phase strengthened ferritic model alloy(1Ti:Fe-20Cr-3Ni-1Ti-3Si,wt.%)has been carefully studied using both advanced experimental(EBSD,TEM and APT)and theoretical(DFT)*** the classic“solid solution and aging”process,the superfine(Fe,Ni)_(2)TiSi-L2_(1)particles densely precipitate within the ferritic grain and subsequently transform into the(Ni,Fe)_(16)Ti_(6)Si_(7)-G *** the meanwhile,the elemental segregation at grain boundaries and the resulting precipitation of a large amount of the(Ni,Fe)_(16)Ti_(6)Si_(7)-G phase are also *** nanoscale microstructural evolutions result in a remarkable increase in hardness(100-300 HV)and severe *** the“cold rolling and aging”process is used,the brittle fracture is effectively suppressed without loss of nano-precipitation strengthening *** yield strength of 1700 MPa with 4%elongation at break is *** key improvement in mechanical properties is mainly attributed to the pre-cold rolling process which effectively avoids the dense precipitation of the G-phase at the grain *** findings could shed light on the further exploration of the precipitation site via optimal processing strategies.

关键词： G-phase Precipitation strengthening Grain boundary segregation Nano-precipitates

Dual nanoprecipitation and nanoscale chemical heterogeneity in a secondary hardening steel for ultrahigh strength and large uniform elongation

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Journal of Materials Science & Technology 2024年第18期185卷 245-258页

作者： Shidong Wang Jinhua Wang Shijie Zhang Daixiu Wei Yang Chen Xuequan Rong Wu Gong Stefanus Harjo Xiaochun Liu Zengbao Jiao Zhigang Yang gang sha Chunxu Wang Guang Chen Hao Chen Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience Nanjing University of Science and TechnologyNanjing 210094China National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China J-PARC Center Japan Atomic Energy AgencyIbaraki 319-1195Japan Institute of Metals College of Materials Science and EngineeringChangsha University of Science&TechnologyChangsha 410114China Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong Kong 999077China Central Iron and Steel Research Institute Beijing 100081China

Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in *** this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging *** chemical heterogeneity involved the enrichment of Mn and Ni in the austenite *** resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni *** hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)*** a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.

关键词： Ultrahigh strength steels Dual-nanoprecipitation Austenite stability TRIP effect Phase transformation