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| 1 | Effects of rare earth elements on inclusions and impact toughness of high-carbon chromium bearing steel显示文摘High-carbon chromium bearing steels with different rare earth (RE) contents were prepared to investigate the effects of RE on inclusions and impact toughness by different techniques. The results showed that RE addition could modify irregular Al2O3 and MnS into regular RE inclusions. With the increase of RE content, the reaction sequence of RE and potential inclusion forming elements should be O, S, As, P and C successively. RE inclusions containing C might precipitate in molten steel and solid state, but the precipitation tem perature was significantly higher than that of carbides in high-carbon chromium bearing steel. For experim ental bearing steels, the volume fraction of inclusions increased steadily with the increase of RE content, but smaller and more dispersed inclusions could be obtained by 0.018% RE content compared with bearing steel without RE, whereas the continuous increase of RE content led to an increasing trend for inclusion size and a gradual deterioration for inclusion distribution. RE addition could improve the transverse impact toughness and isotropy of bearing steel, and for modified highcarbon chrom ium bearing steel by RE alloying, the increase of RE content continuously increased both transverse and longitudinal im pact toughness until excessive RE addition. | Chaoyun Yang Yikun Luan Dianzhong Li Yiyi Li | 2019 | Journal of Materials Science & Technology2019，35，7： | 22 |
| 2 | Theoretical analysis and experimental investigation on flexural performance of steel reinforced ultrahigh toughness cementitious composite (RUHTCC) beams显示文摘UHTCC (ultrahigh toughness cementitious composite), which is a kind of ultrahigh toughness cemen- titious composites material, exhibits pseudo strain hardening feature when subjected to tension load, and has enormous ductility and prominent crack dispersal ability. Accordingly, UHTCC can improve mechanical behavior of ordinary concrete structure especially its durability, and has been regarded as historical breakthrough to traditional cementitious materials. In this paper, the study focuses on flexure behavior of steel reinforced beam made of UHTCC. Based on the plane section assumption, along with two equilibrium equations of force and moment, the formulae to calculate the flexural load capability for the reinforced ultrahigh toughness cementitious composite (RUHTCC) beam were developed under the assumption that the compression stress- strain relationship in the UHTCC material is a bilinear model. Following this, the simplified formulae were further evolved by effective rectangle stress distribution approach in order to facilitate design of practical engineering. Two effective parameters introduced in effective rectangle approach were determined. The mathematical expressions to evaluate limited rein- forcement ratio, flexural stiffness as well as ductility index were proposed, too. Last, two series of dif- ferent reinforcement ratios of the RUHTCC beams were tested in four-point flexure loading. For com- parison purposes, ordinary RC (reinforced concrete) beams also were prepared. Both moment curva- ture curves and load mid-span displacement curves were recorded and compared with the theoretical calculations. A good agreement between them was found, which validates the proposed theoretical formulae. For ductility index, a slightly big difference between the experimental values and the calcu- lated ones exists. The experimental results show that, compared to control RC beams, the RUHTCC beam can improve both flexural capacity and ductility index, and the degree of improvement will de- crease with the increase in the reinforcement ratio. Particularly, the results also reveal that lager crack width in control beams can be greatly reduced by formation of tightly-spaced fine cracks in UHTCC, which offers more durable structures. | XU ShiLang ZHANG XiuFang | 2009 | Science China(Technological Sciences)2009，52，4： | 18 |
| 3 | Effects of Microstructure on the Tensile, Fracture Toughness and Fatigue Behaviour of Gamma Titanium Aluminides显示文摘The effects of microstructure on the deformation and fracture behaviour of two-phase TiAl alloys were investjgated under monotonic and cyclical loading conditions, over a range of temperatu res.The tensile behaviour is analyzed for deformation temperatures between RT and 950℃, Fracture resistance behaviour and toughening mechanisms at RT and 800℃ are analyzed. and the inverse relationship botween ductility and toughness is explained using the crack initiation toughness. The preliminary results of load-controlled fatigue behaviour at 800℃ are interpreted using the tensile behaviour because deformation structure and fracture modes are similar under these two loading | Young- Won (Y-W.) Kim(UES, Inc., Materials Research Division, 4401 Dayton-Xenia Rd., Dayton, OH 45432, USA)(Paper presented at the International Workshop on OrderedIntermetallics 1992, Hangzhou, China) | 1994 | Journal of Materials Science & Technology1994，10，2： | 18 |
| 4 | Theoretical analysis on bending behavior of functionally graded composite beam crack-controlled by ultrahigh toughness cementitious composites显示文摘Ultrahigh toughness cementitious composites (UHTCC) obviously show strain hardening property under tensile or bending loading. The failure pattern of the UHTCC components exhibits multiple fine cracks under uniaxial tensile loading with prominent tensile strain capacity in excess of 3%, with merely 60 μm average crack width even corresponding to the ultimate tensile strain state. The approach adopted is based on the concept of functionally-graded concrete, where part of the concrete, which surrounds the main longitudinal reinforcement in a RC (reinforced concrete) member, is strategically replaced with UHTCC with excellent crack-controlling ability. Investigations on bending behavior of functionally-graded composite beam crack controlled by UHTCC has been carried out, including theo- retical analysis, experimental research on long composite beams without web reinforcement, validation and comparison between experimental and theoretical results, and analysis on crack control. In addition to improving bearing capacity, the results indicate that functionally-graded composite beams using UHTCC has been found to be very effective in preventing corrosion-induced damage compared with RC beams. Therefore, durability and service life of the structure could be enhanced. This paper discusses the development of internal force and crack propagation during loading process, and presents analysis of the internal force in different stages, moment-curvature relationship from loading to damage and calculation of mid-span deflection and ductility index. In the end, the theoretical formulae have been validated by experimental results. | XU ShiLang LI QingHua | 2009 | Science China(Technological Sciences)2009，52，2： | 17 |
| 5 | Highly Stretchable,Elastic,and Sensitive MXene-Based Hydrogel for Flexible Strain and Pressure Sensors显示文摘Electronic skin is driving the next generation of cutting-edge wearable electronic products due to its good wearability and high accuracy of information acquisition.However,it remains a challenge to fulfill the requirements on detecting full-range human activities with existing flexible strain sensors.Herein,highly stretchable,sensitive,and multifunctional flexible strain sensors based on MXene-(Ti_(3)C_(2)T_(x)-)composited poly(vinyl alcohol)/polyvinyl pyrrolidone double-network hydrogels were prepared.The uniformly distributed hydrophilic MXene nanosheets formed a three-dimensional conductive network throughout the hydrogel,endowing the flexible sensor with high sensitivity.The strong interaction between the double-network hydrogel matrix and MXene greatly improved the mechanical properties of the hydrogels.The resulting nanocomposited hydrogels featured great tensile performance(2400%),toughness,and resilience.Particularly,the as-prepared flexible pressure sensor revealed ultrahigh sensitivity(10.75 kPa^(-1))with a wide response range(0-61.5 kPa),fast response(33.5 ms),and low limit of detection(0.87 Pa).Moreover,the hydrogel-based flexible sensors,with high sensitivity and durability,could be employed to monitor fullrange human motions and assembled into some aligned devices for subtle pressure detection,providing enormous potential in facial expression and phonation recognition,handwriting verification,healthy diagnosis,and wearable electronics. | Yao Lu Xinyu Qu Wen Zhao Yanfang Ren Weili Si Wenjun Wang Qian Wang Wei Huang Xiaochen Dong | 2020 | Research2020，，1： | 14 |
| 6 | Experimental study of effect of post processing on fracture toughness and fatigue crack growth performance of selective laser melting Ti-6Al-4V显示文摘For Ti-6Al-4V,a titanium alloy increasingly used in aerospace structure,selective laser melting(SLM)is an attractive additive manufacturing technology,which is attributed to its complex construction capability with high accuracy and good surface quality.In order to obtain qualified mechanical properties,SLM parameters and post processing should be tailored for diverse service conditions.Fracture toughness and fatigue crack growth(FCG)behavior are critical characteristics for damage tolerance evaluation of such metallic structures,and they are affected by post processing technologies significantly.The objective of this study is to obtain the fracture toughness and fatigue crack growth behavior of Ti-6Al-4V manufactured by SLM,and to evaluate the influence of post-SLM thermomechanical treatment and surface machining.Fracture toughness and FCG tests were performed for SLM Ti-6Al-4V in three types of post processing status:as-built,heat treated and hot isostatically pressed(HIPed),respectively.Specimens with as-built and machined surface were tested.The microstructure and fractography were analyzed as well in order to investigate the relevance among manufacture process,microstructure and mechanical properties.The results demonstrate that as-built SLM Ti-6Al-4V presents poor ductility and FCG behavior due to martensitic microstructure and residual stresses.Both heat treatment and hot isostatic pressing improve the plane-stress fracture toughness and FCG performance considerably,while surface machining shows slight effect. | Haiying ZHANG Dengke DONG Shaopu SU An CHEN | 2019 | Chinese Journal of Aeronautics2019，32，10： | 13 |
| 7 | RESEARCH ON THE APPLICATION OF RARE EARTHS IN IRON AND STEEL IN RECENT YEARS显示文摘China has the biggest rare earths resource in the world,no wonder she pays much at-tention to the application of rare earth metals (REM).The application of REM in iron andsteel in China began at the end of 1950’s.The production of REM-treated iron and steelhad been made steady progress in the period of 1980’s.The production of REM-treatediron and steel in 1989 was 1.4 million tons and 250,000 tons respectively.The interest oftreating steel with REM in China keeps growing even in these years,It comes from the nat- | 余宗森 | 1990 | Journal of Rare Earths1990，8，2： | 10 |
| 8 | EXPERIMENTAL STUDY ON PEK -C MODIFIED EPOXIES AND THE CARBON FIBER COMPOSITES FOR AEROSPACE APPLICATION显示文摘The morphological structure of various epoxies toughened with a special amorphous thermoplastic PEK C and their carbon fiber composites were studied by using SEM. For both cases, phase separation and inversion took place to form fine epoxy rich globules dispersing in the PEK C matrix, in which the epoxy rich phase had the absolutely higher volume fraction. The phase structure and the interfacial properties were also studied by means of FTIR, DSC, and DMTA as well. An accompanying mechanical determination revealed that an improved toughness was achieved both in the blend casts and in the carbon fiber composites. A composite structural model was hence suggested. | 李暘暘 益小苏 唐邦明 | 2000 | Chinese Journal of Aeronautics2000，13，4： | 7 |
| 9 | Effect of Tempering Temperature on Strength and Toughness of Novel Carbide-Free Bainite/Martensite Duplex Phase Steel显示文摘The effect of tempering temperature on strength and toughness of the novel carbide free bainite/martensite (CFB/M) duplex steel was investigated. The results showed that the CFB/M mixed microstructure has better tempering stability than single martensite microstructure. The steel has good combination of strength and toughness after tempering at 350 ℃, because the CFB in CFB/M mixed microstructure separates the original austenite grains and causes the refinement of lath martensite, and thermal and mechanical stable retained austenite in CFB is deformed absorbing energy and blocking crack propagation. | LIU Dong-yu BAI Bing-zhe FANG Hong-sheng YANG Zhi-gang ZHANG Chi YAN Wen-yan | 2002 | Journal of Iron and Steel Research(International)2002，9，1： | 7 |
| 10 | A NOVEL METHOD FOR MEASURING AND CHARACTERIZING DYNAMIC FRACTURE-INITIATION TOUGHNESS OF ELASTIC-PLASTIC MATERIALS显示文摘The characterization mad testing methods of the dynamic fracture initiation toughness of elas-tic-plastic materials under tensile impact are studied.By using the self-designed bar-bar tensile impact appa-ratus,a novel test method for studying dynamic fracture-initiation has been proposed based on the one-di-mensional test principle.The curve of average load v.s.displacement(-δ)is smooth until unstablecrack propagation,and the kinetic energy which does not contribute to the crack growth can be removed fromtotal work done by external-force to the specimen.The fracture-initiation point is determined by compliance-changing rate method.The results show that these methods are feasible and effective.Through the analysis ofthe conversion between work and energy of a fracture specimen,the dynamic J-integral is adopted as a char-acteristic parameter for elastic-plastic materials under impact loading.The J-integral is calculated from-△and P-δ curves by using the formula proposed by Rice.The J-integral at fracture initiation is employedto describe the dynamic fracture-initiation toughness of elastie-plastic materials and the experimental resultsindicate that J10can be regarded as a material constant. | Gong Nengping Xia Yuanming | 2002 | Acta Mechanica Solida Sinica2002，15，2： | 7 |
| 11 | Improving toughness of a Mg_(2)Ca-containing Mg-Al-Ca-Mn alloy via refinement and uniform dispersion of Mg_(2)Ca particles显示文摘In this work,two wrought Mg-3.66Al-4.25Ca-0.43 Mn(wt%)alloys with different morphology and distribution of Mg_(2)Ca particles were fabricated by hot extrusion and multi-pass(32)equal channel angular pressing(ECAP).The as-extruded alloy exhibits a banded microstructure with alternately arranged Mg_(2)Ca particle bands,fine α-Mg dynamically recrystallized(DRX)grain bands,and coarse α-Mg deformed grain bands.The Mg_(2)Ca bands are composed of broken Mg_(2)Ca particles which are aggregated and aligned along extrusion direction.The microstructure of ECAP alloy contains complete α-Mg DRX grains and refined Mg_(2)Ca particles which are dispersedly distributed at grain boundaries.Tensile test results show that the as-extruded alloy possesses high ultimate tensile strength(UTS)of 420 MPa and poor fracture elongation of 7%,while the ECAP alloy exhibits improved toughness with UTS of 347 MPa and fraction elongation of 16%.The higher strength of as-extruded alloy is mainly ascribed to the contribution of coarse deformed grains with strong texture,and its poor toughness is resulted from the formation of Mg_(2)Ca bands within which microcracks could form and extend rapidly.On the contrary,the refined and dispersedly distributed Mg_(2)Ca particles are effective to retard crack initiation and impede crack propagation,thereby enhancing the toughness of ECAP alloy significantly. | Huan Liu Chao Sun Ce Wang Yuhua Li Jing Bai Feng Xue Aibin Ma Jinghua Jiang | 2020 | Journal of Materials Science & Technology2020，59，24： | 7 |
| 12 | Toughness and characterization of reactive powder concrete with ultra-high strength显示文摘A number of three-point bending and fracture tests of 200 MPa-level reactive powder concrete (RPC) with the various fiber contents have been conducted to probe the nature and characteristics of tough- ness of RPC200. The contribution of the embedded fibers to improving the crack-resistant capacity, energy absorption capacity and toughness with various deformation mechanisms has been analyzed. Taking account of that the first-crack deformation, peak-load deformation and their improvement varied with the fiber contents and that the deformation mechanism affected differently the performance at the first crack and the peak load, we took the peak-load deformation of plain RPC200 as the reference de- formation to measure the toughness of fibered RPC200. Two toughness indices T2(n?1)(n) and FT2(n?1)(n) have been formulated based on P-δ responses and P-CMOD responses. The indices quantify the tough- ness of RPC200 with the various deformation mechanisms relative to perfectly elastoplastic materials by setting the toughness level 2(n?1) as the initial reference. It is shown that the toughness index T2(n?1)(n) reflects the function of fibers to improve the toughness of RPC with the deformation throughout specimens, but overestimates the contribution to enhancing the toughness in post-peak periods. It underestimates, on other hands, the contribution to improving the toughness in the period from the first crack to the peak load. In contrast, the toughness index FT2(n?1)(n) properly presents the capability that fibers absorb energy and constrain crack propagation in the matrix when the deformation is con- centrated on the open crack. The proposed index unveils the contribution of fibers to toughening RPC200 both in the period from the first-crack to the peak load and in the period of post peak. This characterization method not only reveals the nature of toughness but also levels the toughness of RPC200. It could provide a way to establish an objective toughness characterization for RPC200 and facilitate its applications. | Yang Ju HongBin Liu Jian Chen YuDan Jia PeiHuo Peng | 2009 | Science China(Technological Sciences)2009，52，4： | 7 |
| 13 | Is crack branching under shear loading caused by shear fracture? ——A critical review on maximum circumferential stress theory显示文摘When a crack is subjected to shear force, crack branching usually occurs. Theoretical study shows that the crack branching under shear loading is caused by tensile stress, but not caused by shear fracture. The co plane shear fracture could be obtained if compressive stress with given direction is applied to the specimen, subsequently, calculated shear fracture toughness, K ⅡC , is larger than K ⅠC . A prerequisite of possible occurrence of mode Ⅱ fracture was proposed. The study of shear fracture shows that the maximum circumferential stress theory considered its criterion as a parametric equation of a curve in K Ⅰ, K Ⅱ plane is incorrect; the predicted ratio K ⅡC / K ⅠC =0.866 is incorrect too. [ | 孙宗颀 | 2001 | 中国有色金属学会会刊:英文版2001，11，2： | 6 |
| 14 | INFLUENCE OF THE SECOND THERMAL CYCLE ON COARSE- GRAINED ZONE TOUGHNESS OF X70 STEEL显示文摘The influence of the second thermal cycle on coarse grained zone (CGHAZ) toughness of X70 steel is studied by weld thermal simulation test, scanning electron microscope and electron microprobe. The results show that the CGHAZ toughness is improved after the second thermal cycle but being heated during the intercritical HAZ (ICHAZ). The CGHAZ toughness decreases evidently after being heated during partially transformed zone, which chiefly results from the carbon segregation to the grain boundaries of primal austenite, thus forming high carbon martensite austenite (M A) constituent and bringing serious intercritically reheated coarse grain HAZ (IRCGHAZ) embrittlement. | Y.Wang,T.Han and W.M.Zhao University of Petroleum,Dongying 257062,China | 1999 | Acta Metallurgica Sinica(English Letters)1999，12，5： | 6 |
| 15 | Effects of Rare Earth,Titanium,and Magnesium Additions on Microstructures and Properties of High-boron Medium-carbon Alloy显示文摘In order to improve the toughness and wear resistance of high-boron medium-carbon alloy(HBMCA),a novel wear-resistant HBMCA comprising granular borocarbide was obtained by titanium,magnesium,and rare earth modifications.These modifications gave rise to greatly refined as-cast eutectic borocarbide structures and a less interconnected continuous borocarbide network.Heat treatment mostly produced broken and spheriodized borocarbides that tended to exist as isolated particles in modified HBMCA.The heat treated modified HBMCA exhibited enhanced hardness than pristine and impact toughness was improved significantly to 12.5J/cm^2.In addition,it displayed 2.39 and 1.7times greater wear resistance than high-speed steel(HSS)and high nickel-chromium alloy steel(Cr25)at high temperature(500℃),respectively.Here,the modification mechanisms involving Re_2O_3,TiN,and MgO/MgS heterogeneous nuclei were discussed. | Xiao-li SHI Ye-hua JIANG Rong ZHOU | 2016 | Journal of Iron and Steel Research(International)2016，23，11： | 5 |
| 16 | A Toughness Condition for Fractional(k, m)-deleted Graphs Revisited显示文摘In computer networks, toughness is an important parameter which is used to measure the vulnerability of the network. Zhou et al. obtains a toughness condition for a graph to be fractional(κ, m)-deleted and presents an example to show the sharpness of the toughness bound. In this paper, we remark that the previous example does not work and inspired by this fact, we present a new toughness condition for fractional(κ, m)-deleted graphs improving the existing one. Finally, we state an open problem. | Wei GAO Juan L.G.GUIRAO Yao Jun CHEN | 2019 | Acta Mathematica Sinica,English Series2019，35，7： | 5 |
| 17 | Microstructure and wear resistance of highchromium cast iron containing niobium显示文摘In the paper, the effect of niobium addition on the microstructure, mechanical properties and wear resistance of high chromium cast iron has been studied. The results show that the microstructure of the heattreated alloys is composed of M7C3 and M23C6 types primary carbide, eutectic carbide, secondary carbide and a matrix of martensite and retained austenite. NbC particles appear both inside and on the edge of the primary carbides. The hardness of the studied alloys maintains around 66 HRC, not significantly affected by the Nb content within the selected range of 0.48%-0.74%. The impact toughness of the alloys increases with increasing niobium content. The wear resistance of the specimens presents little variation in spite of the increase of Nb content under a light load of 40 N. However, when heavier loads of 70 and 100 N are applied, the wear resistance increases with increasing Nb content. | Zhang Zhiguo Yang Chengkai Zhang Peng Li Wei | 2014 | China Foundry2014，11，3： | 4 |
| 18 | Influence of Er_2O_3 content on microstructure and mechanical properties of ZTA-TiO_2 composites显示文摘The influence of Er_2 O_3 addition on the phase evolution and mechanical properties of sintered(1600 ℃,4 h) ZTA(yttria stabilized zirconia toughened alumina)-TiO_2 composites was investigated. The SEM and XRD results reveal the formation of a new erbium zirconium oxide,Zr_3 Er_4 O_(12),with a granulate morphology when Er_2 O_3 content is higher than 1 wt%. The grain sizes of both Al_2 O_3 and yttria-stabilized zirconia phases decrease with an increase in the Er_2 O_3 content. The relative density, Vickers hardness and fracture toughness of the composites are found to be strongly dependent on their grain sizes, relative densities and the formation of the Zr_3 Er_4 O_(12) secondary phases. The composite with 5 wt% Er_2 O_3 shows the highest relative density(99.93%), Vickers hardness(1752 HV) and fracture toughness(7.92 MPa·m^(1/2)). | Yudong Sui Li'na Han Yehua Jiang Quan Shan | 2019 | Journal of Rare Earths2019，37，3： | 4 |
| 19 | Bioinspired hierarchical helical nanocomposite macrofibers based on bacterial cellulose nanofibers显示文摘Bio-sourced nanocellulosic materials are promising candidates for spinning high-performance sustainable macrofibers for advanced applications.Various strategies have been pursued to gain nanocellulose-based macrofibers with improved strength.However,nearly all of them have been achieved at the expense of their elongation and toughness.Inspired by the widely existed hierarchical helical and nanocomposite structural features in biosynthesized fibers exhibiting exceptional combinations of strength and toughness,we report a design strategy to make nanocellulose-based macrofibers with similar characteristics.By combining a facile wet-spinning process with a subsequent multiple wet-twisting procedure,we successfully obtain biomimetic hierarchical helical nanocomposite macrofibers based on bacterial cellulose nanofibers,realizing impressive improvement in their tensile strength,elongation and toughness simultaneously.The achievement certifies the validity of the bioinspired hierarchical helical and nanocomposite structural design proposed here.This bioinspired design strategy provides a potential platform for further optimizing or creating many more strong and tough nanocomposite fiber materials for diverse applications. | Huai-Ling Gao Ran Zhao Chen Cui Yin-Bo Zhu Si-Ming Chen Zhao Pan Yu-Feng Meng Shao-Meng Wen Chuang Liu Heng-An Wu Shu-Hong Yu | 2020 | National Science Review2020，7，1： | 4 |
| 20 | Mesoscale fracture behavior of Longmaxi outcrop shale with different bedding angles:Experimental and numerical investigations显示文摘The mechanical properties and fracturing mechanism of shale containing beddings are critically important in shale gas exploitation and wellbore stability.To investigate the effects of shale bedding on crack behavior and fracturing mechanism,scanning electron microscope(SEM)with a loading system was employed to carry out three-point bending tests on Longmaxi outcrop shale.The crack initiation and propagation of Longmaxi shale were observed and recorded by taking photos during loading.The cracking paths were extracted to calculate the crack length through a MATLAB program.The peak load,fracture toughness and fracture energy all increase with the bedding angle from 0°to 90°.The crack length and energy were also found to increase with the bedding angle in the range of 0°-600 and then drop slightly.The fracturing mechanism of shale includes the main crack affected by the bedding angle and disturbed by randomly distributed particles.The main cracking path was accompanied by several microcrack branches which could form an interconnected crack system.When the main crack encounters larger sedimentary particles,it will deflect around the particles and then restore to the initial direction.A numerical technique using extended finite element method(XFEM)coupled with anisotropic cohesive damage criteria was developed,which is able to capture the dependence of crack propagations on bedding angle and sedimentary particles.This study sheds light on understanding and predicting mesoscale fracture behavior of shale with different bedding angles. | Jianping Zuo Jingfang Lu Rojin Ghandriz Jintao Wang Yanhong Li Xiaoyan Zhang Jun Li Hongtao Li | 2020 | Journal of Rock Mechanics and Geotechnical Engineering2020，12，2： | 4 |
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