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Fatigue and fracture behavior of nickel-based superalloy Inconel 718 up to the very high cycle regime

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第10期11卷 727-737页

作者： Xian-feng MA Zheng DUAN Hui-ji shi Ryosuke MURAI Eiichi YANAGISAWA Applied Mechanics Laboratory Department of Engineering Mechanics School of Aerospace Tsinghua University Beijing 100084 China Mitsubishi Heavy Industries Ltd. Tokyo Japan

The fatigue and fracture behavior of nickel-based superalloy Inconel 718 was investigated up to the very high cycle regime under rotary bending tests at room temperature. It was found that this superalloy can still fracture after exceeding 107 cycles. Fractographic analysis revealed that there was a transition from fatigue crack initiation at multi-sites to single initiation with decreasing stress levels. The fracture surface can be divided into four areas according to the appearance, associated with fracture mechanics analysis of the corresponding stress intensity factors. The fracture mechanism dominant in each area was disclosed by scanning electron microscope examination and analyzed in comparison with those obtained from the crack growth tests. Subsequently, life prediction modeling was proposed by estimating the crack initiation and propagation stage respectively. It was found that Chan (2003)'s model for initiation life and the Paris law for growth life can provide comparable predictions against the experimental life.

关键词： Nickel-based superalloy High cycle fatigue (HCF) Fatigue crack initiation Crack growth Life prediction

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes

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Acta Mechanica Sinica 2011年第5期27卷 778-784页

作者： Zheng Duan Xian-Feng Ma Hui-ji shi Ryosuke Murai Eiichi Yanagisawa AML DepartmentofEngineeringMechanicsSchoolofAerospaceTsinghuaUniversity100084BeijingChinaAML Department of Engineering MechanicsSchool of Aerospace Tsinghua University100084 Beijing China Mitsubishi Heavy Industries Ltd. Tokyo Japan

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes were experimentally studied by rotating bending tests,to investigate the effects of the tensile strength obtained by different heat treatment processes on very high cycle fatigue failure *** material with higher tensile strength of 1 710 MPa exhibited typical gigacycle fatigue failure characteristics,whereas one with lower tensile strength of 1 010 MPa showed only traditional fatigue limit during the tests and no gigacycle failure could be found even when the specimen ran up to more than 10 8 *** and fractographic analysis were carried out by an optical microscope （OM） and scanning electron microscope （SEM）.It showed two different crack initiation mechanisms that for the specimen with lower tensile strength the crack prefers surface initiation and for that with higher strength the crack initiates from subsurface inclusions revealed by a fish-eye like microstructure.

关键词： Gigacycle fatigue · S-N curves · Crack initiation · Fractography

Melting geodynamics reveals a subduction origin for the Purang ophiolite,Tibet,China

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Acta Geochimica 2024年第4期43卷 754-773页

作者： Tao Ruan Zhong-jie Bai Wei-Guang Zhu shi-ji Zheng State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China University of Chinese Academy of Sciences Beijing 100049China

The debate regarding whether the Yarlung-Zangbo ophiolite(YZO)on the south of the Qinghai-Tibet Plateau,formed in a mid-ocean ridge(MOR)or a supra-subduction zone(SSZ)setting has remained *** we present petrological,mineralogical,and geochemical data associated with modeling melting geodynamics of the mantle peridotites from the Purang ophiolite in the western segment of the Yarlung-Zangbo Suture Zone(YZSZ)to explore its tectonic *** Purang lherzolites are characterized by the protogranular texture and have abyssal-peridotite-like mineral compositions,including low Cr^(#)(20-30)and TiO_(2) contents(<0.1wt%)in spinel,high Al_(2)O_(3)(2.9wt%-4.4wt%)and CaO(1.9wt%-3.7wt%)contents in orthopyroxene and LREE-depletion in *** of these lherzolites can be modeled by~11%dynamic melting of the DMM source with a small fraction of melt(~0.5%)entrapped within the source,a similar melting process to typical abyssal *** Purang harzburgites are characterized by the porphyroclastic texture and exhibit highly refractory mineral compositions such as high spinel Cr^(#)(40-68),low orthopyroxene Al_(2)O_(3)(<2.2wt%)and CaO(<1.1wt%)*** in these harzburgites are enriched in Sr(up to 6.0 ppm)and LREE[(Ce)N=0.02-0.4],but depleted in Ti(200 ppm,on average)and HREE[(Yb)N<2].Importantly,the more depleted samples tend to have higher clinopyroxene Sr and LREE *** observations indicate an open-system hydrous melting with a continuous influx of slab fluid at a subduction *** modeled results show that these harzburgites could be formed by 19%-23%hydrous melting with the supply rate of slab fluid at 0.1%-1%.The lower clinopyroxene V/Sc ratios in harzburgites than those in lherzolites suggest a high oxidation stage of the melting system of harzburgites,which is consistent with a hydrous melting environment for these *** is therefore concluded that the Purang ophiolite has experienced a transformat

关键词： Melting geodynamics SSZ peridotites MOR peridotites Clinopyroxene Purang ophiolite

Fracture mode identification of low alloy steels and cast irons by electron back-scattered diffraction misorientation analysis

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Journal of Materials Science & Technology 2017年第12期33卷 1582-1595页

作者： Shao-shi Rui Yi-Bo Shang Wenhui Qiu Li-Sha Niu Hui-ji shi Shunsaku Matsumoto Yasuharu Chuman Applied Mechanics Laboratory School of Aerospace EngineeringTsinghua UniversityBeijing 100084China Residential Air Conditioning Division MIDEAFoshan528311China Strength Research Department Research&Innovation CenterMitsubishi Heavy IndustriesLtd.Nagasaki 851-0392Japan

The fracture modes of low alloy steels and cast irons under tensile and fatigue conditions were identified by electron back-scattered diffraction（EBSD） misorientation analysis in this research. The curves of grain reference orientation deviation（GROD） distribution perpendicular to the fracture surface were obtained by EBSD observation, and the characteristics of each fracture mode were identified. The GROD value of the specimen fractured in tension decreases to a constant related to the elongation of corresponding specimen in the far field（farther than 5 mm away from the fracture surface）. The peak exhibits in GROD curves of two smooth specimens and a notched specimen near the fracture surface（within 5 mm away from the fracture surface）, and the formation mechanisms were discussed in detail based on the influences of specimen geometries（smooth or notched） and material toughness. The GROD value of fatigue fractured specimen is close to that at undeformed condition in the whole field, except the small area near the crack path. The loading conditions（constant stress amplitude loading or constant stress intensity factor range K loading） and the EBSD striation formation during fatigue crack propagation were also studied by EBSD observation parallel to the crack path.

关键词： Fracture mode identification Low alloy steels Cast irons Electron back-scattered diffraction (EBSD) Misorientation

Effect of squeeze casting process on microstructures and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy

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Journal of Iron and Steel Research International 2017年第9期24卷 957-965页

作者： Yuan-ji shi Lan-ji Liu Lei Zhang Li-jun Zhang Li Zheng Run-xia Li Bao-yi Yu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870LiaoningChina

The effects of squeeze casting process on microstructure and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy were investigated and the hot-compression tests of gravity casting and squeeze casting alloy were carried out at 350-500°C and *** results show that microstructures of Al-17.5Si-4Cu-0.5Mg alloys were obviously improved by squeeze *** to the decrease of coarse primary Si particles,softα-Al dendrite as well as the fine microstructures appeared,and the mechanical properties of squeeze casting alloys were ***,when the strain rate rises or the deformation temperature decreases,the flow stress increases and it was proved that the alloy is a positive strain rate sensitive *** was deduced that compared with the gravity casting alloy,squeeze casting alloy（solidified at 632 MPa）is more difficult to deform since the flow stress of squeeze casting alloy is higher than that of gravity casting alloy when the deformation temperature exceeds 400°*** stress behavior of Al-17.5Si-4Cu-0.5Mg alloy can be described by a hyperbolic sine form with Zener-Hollomon parameter,and the average hot deformation activation energy Q of gravity casting alloy and squeeze casting alloy is 278.97 and 308.77kJ/mol,respectively.

关键词： Squeeze casting Al-Si-Cu-Mg alloy Hot compression deformation Flow stress Constitutive equation

Effects of Annealing Processes on CuxSi(1-x) Thin Films

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Journal of Wuhan University of Technology(Materials Science) 2016年第1期31卷 31-34页

作者：章嵩 WU Jun HE Zhiqiang 涂溶 shi ji ZHANG Lianmeng State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070China Department of Metallurgy and Ceramics Science Tokyo Institute of Technology Tokyo 152-8552 Japan Institute for Materials Research Tohoku University Sendal 980-8577 Japan

The CuxSi（1-x） thin films have been grown by pulsed laser deposition（PLD） with in situ annealing on Si（001） and Si（111）,*** transformation of phase was detected by X-ray diffraction（XRD）.The results showed that the as-deposited films were composed of Cu on both Si（001） and Si（111）.The annealed thin films consisted of Cu ＋η ＂-Cu3Si on Si（001） while Cu ＋η＇-Cu3Si on Si（111）,respectively,at annealed temperature（Ta）= 300-600℃.With the further increasing of Ta,at Ta= 700℃,there was only one main phase,η＂-Cu3Si on Si（001） while η＇-Cu3Si on Si（111）,*** annealed thin films transformed from continuous dense structure to scattered-grain morphology with increasing Ta detected by field emission scanning electron microscope（FESEM）.It was also showed that the grain size would enlarge with increasing annealing time（ta）.

关键词： CuxSi1-x thin films PLD phase surface morphology

Two new eupodienone lignans from Gymnotheca chinensis

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Chinese Chemical Letters 2014年第3期25卷 463-464页

作者： shi-ji Xiao Fang Chen Li-Sheng Ding Yan Zhou Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization Chengdu Institute of BiologyChinese Academy of Sciences College of Life Science Sichuan University

Two new eupodienone lignans, named gymnothelignan T （1） and gymnothelignan U （2） were isolated from the whole plants of endemic medicinal plant of Gymnotheca chinensis （Saururaceae）. The structures of the new compounds were elucidated by means of HRMS, 1D and 2D NMR. Compound I was tested for cytotoxic activity in HCT15, HCT116, A549, MCF-7 and HepG2 cells and exhibited no appreciable activity against these tested cell lines with IC50 values above 50 μmol/L.

关键词： Gymnotheca chinensisSaururaceaeEupodienoneLignan

Ageing mechanisms and reliability of graphene-based electrodes

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Nano Research 2014年第12期7卷 1820-1831页

作者： Yuanyuan shi Yanfeng ji Fei Hui Hai-Hua Wu Mario Lanza Institute of Functional Nano & Soft Materials Soochow University 199 Ren-Ai Road Suzhou Industrial Park Suzhou Jiangsu 215123China

The development of flexible transparent electrodes for next generation devices has been appointed as the major topic in carbon electronics research for the next five years. Among all candidate materials tested to date, graphene and graphene based nanocomposites have shown the highest performance. Although some incipient anti-oxidation tests have been reported, in-deep ageing studies to assess the reliability of carbon-based electrodes have never been performed before. In this work, we present a disruptive methodology to assess the ageing mechanisms of graphene electrodes, which is also extensible to other carbon- based and two-dimensional materials. After performing accelerated oxidative tests, we exhaustively analyze the yield of the electrodes combining nanoscale and device level experiments with Weibull probabilistic analyses and tunneling current simulation, based on the Fowler-Nordheim/Direct-Tunneling models. Our experiments and calculations reveal that an ultra-thin oxide layer can be formed on the pristine surface of graphene. We quantitatively analyze the consequences of this layer on the properties of the electrodes, and observed a change in the conduction mode at the interface （from Ohmic to Schottky）, an effect that should be considered in the design of future graphene-based devices. Future mass production of carbon-based devices should include similar reliability studies, and the methodologies presented here （including the accelerated tests, characterization and modeling） may help other scientists to move from lab prototypes towards industrial device production.

关键词： electrode local oxidation conductive atomic force microscopy (CAFM) tunneling

Heavy metal availability and impact on activity of soil microorganisms along a Cu/Zn contamination gradient

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Journal of Environmental Sciences 2007年第7期19卷 848-853页

作者： WANG Yuan-peng shi ji-yan LIN Qi CHEN Xin-cai CHEN Ying-xu Department of Chemical and Biochemical Engineering College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China. Department of Environmental Science and Technology Zhejiang University Hangzhou 310029 China

All the regulations that define a maximum concentration of metals in the receiving soil are based on total soil metal concentration. However, the potential toxicity of a heavy metal in the soil depends on its speciation and availability. We studied the effects of heavy metal speciation and availability on soil microorganism activities along a Cu/Zn contamination gradient. Microbial biomass and enzyme activity of soil contaminated with both Cu and Zn were investigated. The results showed that microbial biomass was negatively affected by the elevated metal levels. The microbial biomass-C （Cmic）/organic C （Corg） ratio was closely correlated to heavy metal stress. There were negative correlations between soil microbial biomass, phosphatase activity and NH4NO3 extractable heavy metals. The soil microorganism activity could be predicted using empirical models with the availability of Cu and Zn. We observed that 72% of the variation in phosphatase activity could be explained by the NH4NO3-extractable and total heavy metal concentration. By considering different monitoring approaches and different viewpoints, this set of methods applied in this study seemed sensitive to site differences and contributed to a better understanding of the effects of heavy metals on the size and activity of microorganisms in soils. The data presented demonstrate the relationship between heavy metals availability and heavy metal toxicity to soil microorganism along a contamination gradient.

关键词： heavy metals availability speciation activity soil microorganism