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Effects of elastic-plastic properties of materials on residual indentation impressions in nano-indentation using sharp indenter

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中国有色金属学会会刊：英文版 2012年第S3期22卷 585-595页

作者： Jung-Min LEE Chan-Joo LEE Kyung-Hun LEE Byung-Min KIM Dongnam Regional Division Korea Institute of Industrial Technology Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

One of the primary features of nano-indentation technique is that the contact area induced by an indenter is indirectly measured by a relationship between the penetration depth and the known geometry of the ***,this indirect measurement occasionally leads to inaccurate properties of the indented *** objective of this study is to investigate the effects of E/σr and the strain hardening exponents n of materials on the behaviors of pile-up and sink-in in nano-indentation and to predict n values of materials from the residual indentation *** relations between the residual indentation profile and n value of the indented material were identified by dimensional ***,they were numerically formulated using FE analysis of nano-indentation for 140 different combinations of elastic-plastic parameters such as E,σy and *** parameters of hrp/hm,herp/hm,Rr/hm and HO&P/Hreal were introduced as various dimensionless parameters to represent and quantify the residual indentation profile after *** were subsequently characterized as dimensionless functions using n and E/σr ***,the validity of these functions was verified through 3D FE analysis of nano-indentation for Al 6061-T6 and AISI 1010 materials.

关键词： nano-indentation pile-up sink-in strain hardening exponent FE simulation

Evaluation of microstructure and mechanical properties of Mg-xCe-0.5Zn alloys by nano-indentation

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1240-1243页

作者： K.C.PARK B.H.KIM Y.H.PARK I.M.PARK Department of Material Science and Engineering Pusan National UniversitySan 30 Jangjeon-dongGeumjeong-guBusan 609-735Korea

The microstructure and mechanical properties of Mg-xCe-0.5Zn （x=0.5, 1.5, 2.5, molar fraction, %） alloys were examined using a nano-indentation technique. The alloys were fabricated using a vacuum induction melting method under an argon atmosphere The microstruetures of Mg-xCe-0.5Zn alloys mainly consist ofa-Mg and eutectic Mg12Ce phase. The volume fraction and size of the eutectic Mgl2Ce phase increase with increasing Ce contents. nano-indentation test results show that the indentation hardness and elastic modulus of the eutectic Mg12Ce phase are higher than those of the a-Mg matrix. In addition, the mean indentation hardness and elastic modulus of the Mg-xCe-0.5Zn alloys increase with the Ce addition amount increasing.

关键词： Mg alloys Mg-Ce-Zn rare earth microstructure mechanical properties nano-indentation

Analysis of Solvent Effect on Mechanical Properties of Poly(ether ether ketone) Using nano-indentation

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Chinese Journal of Chemical Physics 2018年第2期31卷 211-215,246页

作者： Tanveer Iqbal Saima Yasin Ahmad Shakeel Hamayoun Mahmood Fahad Nazir Paul F. Luckham Department of Chemical Polymer ＆ Composite Materials Engineering University of Engineering ＆ Technology Lahore KSK Campus 54890 Pakistan Department of Chemical Engineering ＆ Technology Imperial College London South Kensington 5W7 2 AZ UK

Poly（ether ether ketone）（PEEK） is a high-performance semi-crystalline thermoplastic polymer. Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution. In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time. The experiments were performed with a constant loading rate （10 nrn/s） to a maximum indentation displacernent （1000 nrn）. A 30-second hold segrnent was included at the maximum load to account for any creep eft）ors followed by an unloading segrnent to 80% unloading. The indentation hardness and the elastic modulus were corn- puted as a continuous function of the penetration displacernent in the continuous stiffness mode （CSM） indentation. The experirnental data showed that the peak load decreased from -5.2 mN to -1.7 mN as exposure tirne in solvent environrnent increased from 0 to 18 days. The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure tirne in the solvent environrnent. Two empirical models were used to fit the experirnental data of hardness as a function of exposure tirne which showed a good agreernent with the experirnental values.

关键词： Solvent nano-indentation Poly(ether ether ketone) Modulus Hardness

Determinationofelasticmodulus of claystone:nano-/micro-indentation andmeso-compression tests used to investigate impact of alkaline fluid propagation over 18 years

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第3期9卷 129-136页

作者： Danièle Bartier Christophe Auvray GeoRessources UMR 7359 Université de Lorraine CNRS CREGU Campus Aiguillettes Vandoeuvre-les-Nancy 54500 France

Micro-mechanical properties of a claystone were tested after undergoing alkaline perturbation on site(Tournemire,CD borehole)for 18 *** a saturated context and outside the excavation disturbed zone(EDZ),the claystone exhibits a 11.6-mm black rim at the cement/paste interface,which shows a different mechanical behaviour from the rest of the *** sets of measurements of elastic modulus were performed using:(i)nano-indentation tests with a constant indentation depth of 2 mm,(ii)microindentation tests with a constant indentation depth of 20 mm,and(iii)meso-compression tests with a constant displacement of 200 *** increase of the modulus of deformability in the black rim is between 15 GPa and 20 GPa according to the ***,an overall decrease of the modulus of deformability from the smallest to the largest scale is observed in each *** view of the mineralogy and petrographic observations,higher values of modulus of deformability in the black rim are related to carbonate content and its *** of cementitious carbonates as inclusions and very thin partings leads to hardening of the claystone.

关键词： Claystone Elastic modulus nano-indentation Micro-indentation Meso-compression Carbonate Claystone/cement paste contact

Structural,mechanical and electronic properties of precipitates in Mg−Zn alloys

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Transactions of Nonferrous Metals Society of China 2024年第8期34卷 2507-2520页

作者： Tian-zhi ZHANG Yang-zhen LIU Qing-yun FU Bai-song GUO Wei-hong JIN Zhen-tao YU Institute of Advance Wear&Corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China Shaoguan Research Institute of Jinan University Shaoguan 512027China Stomatological Hospital Southern Medical UniversityGuangzhou 510280China

To accelerate the development and design of magnesium(Mg)alloys,the structural and mechanical properties of important precipitates in Mg−Zn alloys were studied by experiments and density functional *** nano-indentation tests revealed that the hardness of the precipitates initially increased and then decreased with increasing Zn content,and was significantly higher than that of pure Mg and *** calculation results revealed that the precipitates stability initially increased and then decreased with increasing Zn *** bulk moduli of the precipitates increased,whereas their shear and Young’s moduli initially increased and then decreased with increasing Zn *** decreasing order of ductility for these compounds is MgZn_(2)>Mg_(21)Zn_(25)>Mg_(2)Zn_(11)>Mg_(4)Zn_(7).The surface profiles of the compounds revealed that they are obvious *** the degree of covalency and bond length of covalent bonds initially increased and then decreased with increasing Zn content.

关键词： Mg−Zn alloy nano-indentation modulus hardness chemical bonding

Surface modification of 316L stainless steeldiamond-like carbon films

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Journal of Iron and Steel Research International 2020年第7期27卷 867-874页

作者： Rui-wu Li Zheng Zhang Jian-wei Li Ke-xin Ma Yuan-yuan Guo Yan-wen Zhou Fa-yu Wu School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina Liaoning Censcience Industrial Co. Ltd.Research and Design InstituteLiaoyang 111200LiaoningChina

The diamond-like carbon(DLC)film on 316L stainless steel substrate was preparedpulsed plasma-enhanced chemical vapor deposition,and the performance of the films was optimizedregulating the pulse *** and properties of DLC film on 316L stainless steel were characterizedatomic force microscopy,field-emission scanning electron microscopy,Raman spectra,nano-indenter and electrochemical *** results showed that DLC films with smooth and dense morphology have a low friction coefficient and high nano-indentation hardness,and the surface hardness of 316L stainless steel substrate was enhancedmore than 3 *** mechanical properties of DLC films and their bond with 316L stainless steel could be further optimizedincreasing pulse *** films on 316L stainless steel substrate increased the self-corrosion potential0.173 V and decreased self-corrosion current99%,which significantly improved the anti-corrosive properties of 316L substrate.

关键词： 316L stainless steel Diamond-like carbon film Plasma enhanced chemical vapor deposition Frictional wear nano-indentation Corrosion resistance

Small-scale analysis of brittle-to-ductile transition behavior in pure tungsten

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Journal of Materials Science & Technology 2022年第10期105卷 242-258页

作者： Yeonju Oh Won-Seok Ko Nojun Kwak Jae-il Jang Takahito Ohmura Heung Nam Han Department of Materials Science and Engineering&Research Institute of Advanced Materials Seoul National UniversitySeoul 08826South Korea School of Materials Science and Engineering University of UlsanUlsan 44610South Korea Division of Materials Science and Engineering Hanyang UniversitySeoul04763South Korea National Institute for Materials Science 1-2-1 SengenTsukubaIbaraki 305-0047Japan

Tungsten as a material exhibits broad and increasingly important applications;however,the characterization of its ductile-to-brittle transition(BDT)is currently limited to large-scale scenarios and destructive *** this study,we overcome this challenge by implementing small-scale techniques to provide a comprehensive understanding of the BDT behavior of pure *** order to predict the failure mode at various temperature ranges,the practical fracture analysis diagram has been proposed to describe the resistance to shear flow and cracking behavior with *** temperature nano-indentation tests have provided the inherent mechanical responses corresponding to the maximum shear stress at various temperatures,which is required for dislocation activities in an atomic scaled activation *** one hand,atomistic simulations have provided the temperature dependence of brittle fracture stress,where the atomic bonds break due to intergranular or intragranular *** considered four tungsten specimens having various microstructures prepared using different processing conditions of cold-rolling and post-annealing,and their BDT ranges were inferred using the obtained fracture analysis diagram with the statistical data *** fracture analysis diagram of each specimen obtained were compared with the direct observation of fracture responses in macroscopic mechanical tests,which conclusively indicated that the small-scale inherent mechanical properties are greatly relevant to the macroscopic BDT behavior in pure *** on the BDT estimations by small-scale characterization,we provided further insights into the factors affecting the BDT behavior of tungsten,focusing on the contributions of different types of dislocations.

关键词： Brittle-to-ductile transition nano-indentation Molecular dynamics Dislocation Tungsten

Morphology and Mechanical Properties of Vibratory Organs in the Leaf-cutting Ant （Atta cephalotes）

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Journal of Bionic Engineering 2018年第4期15卷 722-730页

作者： Guang Yao Lin Feng Deyuan Zhang Xinggang Jiang School of Mechanical Engineering and Automation Beihang University Beijing 100191 China Beijing Advanced Innovation Center for Biomedical Engineering Beihang University Beijing 100083 China

The ultrasonic scalpel has a number of excellent properties; however, its use in in vivo surgery is limited since the scalpel is not flexible enough. Changing the mechanism of ultrasonic vibration can allow the ultrasonic scalpel to bend. This paper reveals the mecha- nism of vibration generation of leaf-cutting ants, which is based on the microstructural and mechanical properties of special organs that produce the vibrations. Mierostructural characteristics of cross-sections of the vibratory organ of Atta cephalotes were observed using scanning electron microscopy. It was found that the scraper perfectly matches the file plate dorsoventrally; however, the file teeth cannot catch the scraper. An exploration of the kinematics of the file-scraper device was subsequently carried out to reveal a face-to-face contact mode, facilitating a gentler engagement process. For the first time, the mechanism of vibration generation of leaf-cutting ants was inves- tigated using a laser micrometer and high-speed camera. Results reveal the file-scraper device significantly amplifies the input frequency by 125 times, and magnification depends mainly on the tooth spacing and speed of engagement. Finally, nanoindentation tests were performed on file and scraper samples. The results show that they have similar mechanical properties, which greatly reduces friction and wear. This paper may provide theoretical guidance for the develooment of bionic vibration generators.

关键词： leaf-cutting ant vibration mechanism file-scraper device nano-indentation

Plasma Spray Deposition of HA-TiO2 on β-phase Ti-35Nb-7Ta-5Zr Alloy for Hip Stem: Characterization of Bio-mechanical Properties, Wettability, and Wear Resistance

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Journal of Bionic Engineering 2020年第5期17卷 1029-1044页

作者： Harjit Singh Chander Prakash Sunpreet Singh School of Mechanical Engineering Lovely Professional UniversityPhagwaraPunjab-144411India Mechanical Engineering National University of SingaporePincode-119244Singapore

In this work,a biomimetic coating of hydroxyapatite(HA)-and titania(TiO2)was deposited on low elastic β-phase Ti-35Nb-7Ta-5Zr(β-TNTZ)alloy by plasma spray deposition technique for orthopedic *** effect of TiO2 reinforcement on microstructure,mechanical properties,and bioactivity was *** morphology,coating thickness,elemental composition,and phase composition of the developed coatings were *** biomechanical behavior of the deposited coatings was investigated in terms of surface hardness,elastic modulus,and adhesion *** was found from the morphological investigation that the TiO2 reinforcement improves the microstructure and prevents the formation of defects in the *** biomimetic HA-TiO2 coated surface possessed pores,size ranging from 200 nm-600 nm that benefits the apatite growth and *** EDS spectrum,mapping,and XRD analysis show that the deposited layerβ-TCP,CaO,TTCP,TiO2 *** HA-TiO2 coating exhibits a very dense and thick layer of 100μm-125am that exhibits excellent adhesion strength to offer mechanical interlocking to prevent *** alloying of TiO2 improves the hardness from 1.67 GPa to 2.95 GPa that enhances the wear *** was found that HA-TiO2 coating exhibits better hydrophilic and biocompatible surface as compared to HA-coating.

关键词： β-phase Ti-35Nb-7Ta-5Zr alloy plasma spray porosities bio-ceramic coating nano-indentation hardness bond strength wettability