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| 1 | Effect of thermal cycling on the mechanical properties of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) alloy显示文摘The effect of thermal cycling treatment on mechanical properties and thermal stability of a Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass is investigated.The metallic glassy samples are sealed into quartz tubes under high vacuum condition,and liquid nitrogen together with electric furnace are used to control a periodical temperature variation between 196℃ and 150℃.The structure and properties of the tested samples for different thermal cycles have been examined by X-ray diffraction analysis,mechanical properties measurement and thermal analysis.It has been found that the structure and properties of the samples do not show a significant change even after 200 cycles,which suggests Zr41Ti14Cu12.5Ni10Be22.5 alloy as having potential in aerospace environment. | WANG Xin SHAO Yang GONG Pan YAO KeFu | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，12： | 10 |
| 2 | Work toughening effect in Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5) bulk metallic glass显示文摘Work hardening is a well-known phenomenon occurring in crystalline metals during deformation,which has been widely used to increase the strength of metals although their ductility is usually reduced simultaneously. Here we report that the plastic strain of Zr41Ti14Cu12.5Ni10Be22.5 (at.%) bulk metallic glasses has been increased from 0.3% for the as-cast sample to 2.5%-8.0% for samples that have experienced pre-deformation under constrained conditions. The pre-deformed glassy alloys possess more free volume and abundant introduced shear bands,which are believed to promote the activation of shear bands in post-deformation and result in an increase in plasticity. The orientation of the pre-introduced shear bands relative to the loading direction will affect the deformation behavior of pre-deformed samples. The present results show that pre-deformation of this glassy alloy will result in work toughening. This work toughening effect can be removed by isothermal annealing at a sub-Tg (glass transition) temperature,which causes annihilation of free volume and healing of shear bands. | QIU ShengBao GONG Pan YAO KeFu | 2011 | Chinese Science Bulletin2011，56，36： | 6 |
| 3 | Ti-Zr-Be-Fe quaternary bulk metallic glasses designed by Fe alloying显示文摘A series of Ti-Zr-Be-Fe bulk metallic glasses(BMGs)with good glass-forming ability(GFA)and high specific strength have been developed.With different alloying routes and content of Fe,it is found that these alloys exhibit different GFA and mechanical properties.The effects of Fe addition on the GFA and mechanical properties of Ti-Zr-Be alloy are systemically investigated.The possible mechanisms for the improvement or damage to the GFA by addition of Fe can be interpreted in view of the mixing enthalpy,atomic size differences and electronegativity differences of the alloys,while the mechanical properties strongly depend on the Poisson’s ratio and free volume concentration.The experimental results also show that alloying technology is an effective method to improve the GFA and mechanical properties of Ti-Zr-Be glassy alloy. | GONG Pan WANG Xin SHAO Yang CHEN Na YAO KeFu | 2013 | Science China(Physics,Mechanics & Astronomy)2013，56，11： | 6 |
| 4 | A bulk metal/ceramic composite material with a cellular structure显示文摘A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20―40 μm, while a thickness of the cell wall is about 1―2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property. | ZHAO Zhankui YAO Kefu LI Jingfeng | 2006 | Chinese Science Bulletin2006，51，2： | 5 |
| 5 | Pd-Si binary bulk metallic glass显示文摘Pd80+xSi20-x (x=0,1,and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing and water quenching or air cooling. Thermal analysis results show that with increasing Si content,the glass transition temperature Tg,the initial crystallization temperature Tx and the onset crystalliza-tion temperature Tp of Pd-Si binary glassy alloys increase. Moreover,the super-cooled liquid region reaches 61 K. It indicates that Pd-Si binary alloys possess large glass forming ability,which can be greatly improved by fluxing treatment. | YAO KeFu CHEN Na | 2008 | Science China(Physics,Mechanics & Astronomy)2008，51，4： | 3 |
| 6 | Simulated photo-degradation of dissolved organic matter in lakes revealed by three-dimensional excitation-emission matrix with regional integration and parallel factor analysis显示文摘Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(Radj2)(0.963-0.998).The photo-degradation rate constants(kn) showed differences of three orders of magnitude,from 1.09 × 10-6 to 4.02 × 10-4 min-1,and half-life of multi-order model(T1/2n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(PⅠ,n) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(PⅡ,n,while the largest decrease ratio was found for C3 components,and the lowest T1/2n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM. | Jin Zhang Fanhao Song Tingting Li Kefu Xie Huiying Yao Baoshan Xing Zhongyu Li Yingchen Bai | 2020 | Journal of Environmental Sciences2020，32，4： | 3 |
| 7 | Plastic deformation behavior of Fe_(40)Ni_(40)P_(14)B_6 bulk metallic glass investigated by nanoindentation显示文摘Fe40Ni40P14B6 bulk metallic glass rods have been prepared by water quenching the fluxed alloy. The deformation behavior was investigated by nanoindentation tests and compressing tests. The average hardness and elastic modulus of the as-prepared Fe40Ni40P14B6 BMG (bulk metallic glass) measured by nanoindentation tests are 8.347 and 176.61 GPa respectively. The displace- ment-load curve shows “pop-in” characteristics which correspond to the loading rate bursts. Many shear bands around the indent were observed. The as-prepared Fe-based BMG exhibits a compressive plastic strain of 5.21%, which is much larger than that of other Fe-based glassy alloys and most of other BMGs. | Changqing Zhang and Kefu Yao Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China | 2007 | International Journal of Minerals,Metallurgy and Materials2007，15，S1： | 2 |
| 8 | Structural and magnetic properties of Fe_3O_4 nanoparticles prepared by arc-discharge in water显示文摘By using a simple and low-cost arc-discharge method in deionized water, high purity Fe3O4 nanoparti- cles have been synthesized on large scale. The structure of these nanoparticles has been studied by means of transmission electron microscope and X-ray diffraction. The synthesized Fe3O4 nanoparticles show well-defined spherical shape, with diameters ranging from 10 to 30 nm and the average diameter about 20 nm. By investigating the effects of the different processing conditions, optimum parameters were obtained. Moreover, the size of the as-grown nanoparticles can also be controlled through ad- justing the processing parameters. These Fe3O4 nanoparticles were magnetic materials, showing saturation magnetization of 64.97 emu/g at room temperature. | FAN XiaoLing YAO KeFu | 2007 | Chinese Science Bulletin2007，52，20： | 2 |
| 9 | Influence of flux treatment on the glass forming ability of Pd-Si binary alloys显示文摘Pd81Si19 amorphous alloys were prepared by combination methods of melt spinning and B2O3 flux treatment. A compari- son between the ribbons prepared from the fluxed ingots and the non-fluxed ones has been carried out. The result reveals that after fluxing treatment the glass transition temperature of the as-prepared glassy ribbons is reduced while the initial crystallization tem- perature is enhanced. It results in that the supercooled liquid region (defined as the difference between the initial crystallization tem- perature and the glass transition temperature) of the glassy alloy treated with fluxing technology has been increased from 31 to 42 K. This shows that fluxing technique can enhance the glass forming ability (GFA) of the binary alloy and improve the thermal stability of supercooled liquid of the glassy alloy. | Na Chen, Kefu Yao, and Fang Ruan Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China. | 2007 | International Journal of Minerals,Metallurgy and Materials2007，15，S1： | 2 |
| 10 | Research on the Numerical Simulation of the Tempering Process of Steel显示文摘In this paper, the kinetics and creeping behavior in the tempering of were experimentally investigated in detail with two kinds of large-forging steel. The martensitic and bainitic transformations were expressed as functions of the tempering parameter. The kinetics of phase transformation of the retained austenite was described by the Avrami equation. Based on the elastoplastic-creeping theory, the constitutive relations for steel tempering process were obtained, and an FEM code was developed. The program was verified with the tempering process of a cylindrical specimen, and the quenching-tempering process of a turbine rotator was analyzed. | Wei Shi, Xuejun Xu, Kefu Yao, Zhuang Liu Mechanical Engineering Department, Tsinghua University, Beijing 100084, China | 2000 | Journal of Shanghai Jiaotong university(Science)2000，5，1： | 2 |
| 11 | Microstructural evolution in high power laser cladding of Stellite 6 WC layers 显示文摘 | Zhong Minlin Liu Wenjin Yao Kefu | 2002 | Surface and Coatings Technology2002，157，： | 1 |
| 12 | Microstructure, phase stability and mechanical properties of Nb–Ni–Ti–Co–Zr and Nb–Ni–Ti–Co–Zr–Hf high entropy alloys显示文摘Owning to their excellent thermal stability and high strength at elevated temperature,high entropy alloys(HEAs) possess great potential for the application in aviation and aerospace fields.In present work,two novel Nb-Ni-Ti-Co-Zr and Nb-Ni-Ti-Co-Zr-Hf HEAs were prepared by arc melting and copper mold suction-casting method.The microstructure,phase stability,mechanical properties at room temperature and elevated temperature of the two HEAs were studied.Both of the HEAs possess high yield stress at room temperature,especially for the Nb-Ni-Ti-Co-Zr(with 2331 Mpa).In addition,the Nb-Ni-Ti-Co-Zr HEA exhibited high yield stress of 564 Mpa at elevated temperature of 800 ℃ and large compressive plastic strain(more than 50%at 800 ℃).Nb-Ni-Ti-Co-Zr-Hf alloy showed new phase precipitation at 800 ℃,whereas the structure of Nb-Ni-Ti-Co-Zr was more stable,which is one of the reason why it possesses high strength at room temperature and elevated temperature.The high temperature properties of the Nb-Ni-Ti-Co-Zr HEA make it promising for high temperature application. | Zhidong Han Xue Liu Shaofan Zhao Yang Shao Jinfeng Li Kefu Yao | 2015 | Progress in Natural Science:Materials International2015，25，5： | 1 |
| 13 | Microstructural evolution in high power laser cladding of Stellite 6+WC layers显示文摘 | Zhong Minlin Liu Wenjin Yao Kefu | 2002 | Surface and Coatings Technology2002，157，： | 1 |
| 14 | Influence of acid treatment on the activity of carbon nanotube- supported catalyst显示文摘 | Li Chunhua Yao Kefu Liang Ji | 2003 | Carbon2003，41，： | 1 |
| 15 | TEM OBSERVATION OF LOCAL DEFORMATION BAND AT CRACK TIP显示文摘The thin foil specimen of a ferrite-austenite duplex stainless steel was tensiled under transmis-sion electron microscope(TEM).It was found that both in ferrite and austenite the localdeformation band at crack tip was formed near to the crack propagating direction.Its forma-tion was related with the crack tip Schmid factor,dislocation shielding,latent hardening andhardening coefficient.When the crack tip emitted dislocations to a slip system by the action ofpure mode Ⅱ stress resolute,and the decreasing rate of hardening coefficient was suitable,lo-cal deformation band was easy to form. | YAO Kefu University of Science and Technology Beijing,Beijing,ChinaTANG Naivong CHEN Nanping Tsinghua University,Beijing,China | 1992 | Acta Metallurgica Sinica(English Letters)1992，5，3： | 1 |
| 16 | Application of carbon nanotube supported nickel/aluminum mixed oxide in synthesis of carbon nanotubes显示文摘 | Li Chunhua Zhao Yun Yao Kefu | 2003 | Carbon2003，41，： | 1 |
| 17 | Core loss analysis of Finemet type nanocrystalline alloy ribbon with different thickness显示文摘Nanocrystalline soft magnetic materials are widely used in power electronic applications due to their high permeability,magnetization and low core loss.In this paper,Fe_(73.5)Cu_1Nb_3Si_(15.5)B_7(at%)nanocrystalline alloy ribbons,with ultra-thin thickness of 14μm,and also 18 and 22μm,were prepared by a planar flow casting method with a single roller device.Soft magnetic properties of these ribbons were analyzed after nanocrystallization annealing.The experiments were conducted on toroidal samples using IWATSU B-H Analyzer over a frequency range of 10–100 kHz,at induction amplitudes of 100–500 m T,at room temperature.It was found that the excess eddy current loss P_(ex)was the dominant factor in the overall core loss above 10 k Hz.The toroidal samples made of the 14μm thickness ribbon exhibit very low total core loss of 48 W/kg at a frequency of100 kHz and magnetic flux density of 300 mT.The ratio of the P_(ex)was up to 89%at 100 kHz.The ribbon with lower thickness exhibits lower P_(ex)and therefore lower total core loss.The domain structure evidences were found.It indicates that the ribbons with small thickness are preferable for application in high frequency condition. | Zhun Li Kefu Yao Deren Li Xiaojun Ni Zhichao Lu | 2017 | Progress in Natural Science:Materials International2017，27，5： | 1 |
| 18 | Amorphous magnetic semiconductors with Curie temperatures above room temperature显示文摘Recently, amorphous magnetic semiconductors as a new family of magnetic semiconductors have been developed by oxidizing ferromagnetic amorphous metals/alloys. Intriguingly, tuning the relative atomic ratios of Co and Fe in a Co-Fe-Ta-B-O system leads to the formation of an intrinsic magnetic semiconductor. Starting from high Curie-temperature amorphous ferromagnets, these amorphous magnetic semiconductors show Curie temperatures well above room temperature. Among them, one typical example is a p-type Co28.6Fe12.4Ta4.3B8.7O46 magnetic semiconductor, which has an optical bandgap of ~2.4 eV, roomtemperature saturation magnetization of ~433 emu/cm3, and the Curie temperature above 600 K. The amorphous Co28.6Fe12.4Ta4.3B8.7O46 magnetic semiconductor can be integrated with n-type Si to form p-n heterojunctions with a threshold voltage of ~1.6 V, validating its p-type semiconducting character. Furthermore, the demonstration of electric field control of its room-temperature ferromagnetism reflects the interplay between the electricity and ferromagnetism in this material. It is suggested that the carrier density, ferromagnetism and conduction type of an intrinsic magnetic semiconductor are controllable by means of an electric field effect. These findings may pave a new way to realize magnetic semiconductor-based spintronic devices that work at room temperature. | Na Chen Kaixuan Fang Hongxia Zhang Yingqi Zhang Wenjian Liu Kefu Yao Zhengjun Zhang | 2019 | Journal of Semiconductors2019，40，8： | 1 |
| 19 | Microstructural evolution in high power laser cladding of stellite 6+WC layers显示文摘 | Zhong Minlin Liu Wenjin Yao kefu | 2002 | Surface & Coatings Technology2002，157，： | 1 |
| 20 | Microstructural evolution in high power laser cladding of Stellite 6+WC layers显示文摘 | Minlin Zhong Wenjin Liu Kefu Yao Jean-Claude Goussain Cécile Mayer Ahim Becker | 2002 | Surface & Coatings Technology2002，，2： | 1 |
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