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strain rate sensitivity OF ULTRAFINE-GRAINED Cu WITH NANOSIZED TWINS

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 313-318页

作者： L.X. Liu X.H. Chen L. Lu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

An ultrafine-grained Cu sample with a high density of growth twins was synthesized by means of pulsed electrodeposition technique. The strain rate sensitivity of the Cu sample was measured by strain rate cycling tests under tension. The effects of grain size as well as twin density on the strength and strain rate sensitivity were discussed.

关键词： copper nanosized twin strain rate sensitivity deformation mechanism

strain rate sensitivity and activation volume of electrodeposited nanocrystalline Ni and Ni-Co alloys

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Rare Metals 2007年第S1期26卷 134-138页

作者： LIAN Jianshe,GU Changdong,LI Guangyu,and JIANG Qing Key Laboratory of Automobile Materials,Ministry of Education,Department of Materials Science and Engineering,Jilin University,Changchun 130025,China Jilin Univ Dept Mat Sci & Engn Minist Educ Key Lab Automobile Mat Changchun 130025 Peoples R China

Tensile deformation behaviors of the electrodeposited 40 nm grain sized Ni,25 nm Ni-1.7 wt.%Co,and 13 nm Ni-8.6 wt.%Co alloys at various strain rates and room temperature were reviewed with emphasis on strain rate sensitivity and activation volume,*** is found that the strain rate sensitivity and activation volume were strongly grain size *** analytic model based on the bow out of a single dislocation well predicted the relationship between the strain rate sensitivity and the activation volumes for these nanocrystaline metals.

关键词： nanocrystalline mechanical properties strain rate sensitivity activation volume Ni-Co alloy Ni

strain rate sensitivity of closed cell aluminium fly ash foam

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Transactions of Nonferrous Metals Society of China 2013年第4期23卷 1080-1089页

作者： Manmohan DASS GOEL VASANT A.MATSAGAR Anil K.GUPTA Steffen MARBURG CSIR-Advanced Materials and Processes Research Institute(AMPRI) Council of Scientific and Industrial Research(CSIR)Bhopal-462064India Department of Civil Engineering Indian Institute of Technology(IIT) DelhiNew Delhi-110016India Department of Aerospace Engineering University of German Armed ForcesNeubiberg-85577MunichGermany

With the increasing use of metal foams in various engineering applications, investigation of their dynamic behaviour under varying strain rate is necessary. Closed cell aluminium fly ash foam developed through liquid metallurgy route was investigated for its stress--strain behaviour at different strain rates ranging from 700 s^-1 to 1950 s^-1. The numerical model of split Hopkinson pressure bar （SHPB） was simulated using commercially available finite element code Abaqus/Explicit. Validation of numerical simulation was carried out using available experimental and numerical results. Full scale stress--strain curves wez＇e developed for various strain rates to study the effect of strain rate on compressive strength and energy absorption. The results showed that the closed cell aluminium fly ash foam is sensitive to strain rate.

关键词： high strain rate metal foam strain rate sensitivity numerical simulation split Hopkinson pressure bar

Positive strain rate sensitivity and Deformation Behavior of a Fe–29Mn–3Al–3Si TWIP Steel

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Acta Metallurgica Sinica(English Letters) 2022年第11期35卷 1825-1836页

作者： Shucheng Shen Cuilan Wu Pan Xie Yuanrui Liu Center of High Resolution Electron Microscopy College of Materials Science and EngineeringHunan UniversityChangsha 410082China

The Fe-29 Mn-3 Al-3 Si twin-induced plasticity(TWIP)steel is used to conduct quasi-static compression and dynamic impact deformation with strain rates ranging from 8.3×10^(-4) to 3800 s^(-1).The microstructures and properties of deformed samples under different strain rates were investigated *** results show that positive strain rate sensitivity was observed with the increase in strain rates and that there was a significant difference in strain rate sensitivity factor(m)between quasi-static compression(m=0.029)and dynamic impact deformation(m=0.190).Compared to the quasi-static compression,the dynamic impact deformation exhibited higher yield *** examination reveals that the primary twins were frequently found during the quasi-static compression process,and the secondary twins were rarely ***,the secondary and multi-fold deformation twins were florescent in the dynamic impact *** the initial stage of dynamic impact deformation,partial dislocations and staking faults on multiple conjugate{111}planes were simultaneously activated and produced a large number of Lomer-Cottrell dislocations,resulting in a large increase in yield strength during dynamic impact.

关键词： TWIP steel Dynamic deformation strain rate sensitivity Multi-fold deformation twins

Unusual He-ion irradiation strengthening and inverse layer thickness-dependent strain rate sensitivity in transformable high-entropy alloy/metal nanolaminates:A comparison of Fe_(50)Mn_(30)Co_(10)Cr_(10)/Cu vs Fe_(50)Mn_(30)Co_(10)Ni_(10)/Cu

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Journal of Materials Science & Technology 2022年第21期116卷 199-213页

作者： Y.F.Zhao H.H.Chen D.D.Zhang J.Y.Zhang Y.Q.Wang K.Wu G.Liu J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

In this work,we prepare transformable HEA/Cu nanolaminates(NLs)with equal individual layer thick-ness(h)by the magnetron sputtering technique,i.e.,Fe_(50)Mn_(30)Co_(10)Cr_(10)/Cu and Fe_(50)Mn_(30)Co_(10)Ni_(10)/Cu,and comparatively study He-ion irradiation effects on their microstructure and mechanical *** ap-pears that the as-deposited HEA/Cu NLs manifest two size h-dependent hardness regimes(i.e.,increased hardness at small h and hardness plateau at large h),while the He-implanted ones exhibit monotonically increased *** to the fashion that smaller h renders less irradiation hardening in bimetal NLs,the Fe_(50)Mn_(30)Co_(10)Cr_(10)/Cu NLs manifest the trend that smaller h leads to greater irradiation *** contrast,the Fe_(50)Mn_(30)Co_(10)Ni_(10)/Cu NLs exhibit the maximum irradiation hardening at a critical h=50 *** this critical size,smaller h results in lower radiation hardening(similar to bimetal NLs),while above this size,smaller h results in greater radiation hardening(similar to Fe_(50)Mn_(30)Co_(10)Cr_(10)/Cu NLs).Moreover,these transformable HEA/Cu NLs display inverse h-dependent strain rate sensitivity(SRS m)before and after He-ion ***,compared with as-deposited samples,the irradi-ated Fe_(50)Mn_(30)Co_(10)Cr_(10)/Cu NLs display reduced SRS,while the irradiated Fe_(50)Mn_(30)Co_(10)Ni_(10)/Cu NLs dis-play enhanced *** unusual size-dependent irradiation strengthening and inverse h effect on SRS in irradiated samples were rationalized by considering the blocking effects of He bubbles on dislocation nucleation and motion,i.e.,dislocations shearing or bypassing He bubbles.

关键词： High entropy alloy/metal nanolaminates Interfaces Irradiation hardening strain rate sensitivity Size effects

Inverse grain-size-dependent strain rate sensitivity of face-centered cubic high-entropy alloy

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Journal of Materials Science & Technology 2021年第27期86卷 251-259页

作者： Lili Xiao Ping Huang Fei Wang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an710049China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi'an Jiaotong UniversityXi’an710049China

It is well documented that the strain rate sensitivity(m)increases at refined grain size for face-centered cubic(FCC)metals and *** a series of nanoindentation testing,however,we experimentally demonstrated a striking departure from conventional FCC metals that Co Cr Fe Mn Ni high entropy alloy(HEA)with FCC lattice structure exhibits monotonously decreased m as grain size reduced fromμ30.3m to 7.2 ***,the apparent activation volume v*,which generally shows an opposite trend of m,exhibited the identical decreasing trend with reduced grain size as that of *** an unusual trend of m and its correlation with v*in the FCC HEA alloys can be understood by a distinct deformationmechanism-transitions and unique dislocation morphology evolution that differs from conventional FCC metals.

关键词： High entropy alloy strain rate sensitivity Activation volume Deformation mechanism Wavy dislocation

strain hardening behavior, strain rate sensitivity and hot deformation maps of AISI 321 austenitic stainless steel

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International Journal of Minerals,Metallurgy and Materials 2021年第11期28卷 1799-1810页

作者： Mehdi Shaban Ghazani Beitallah Eghbali Department of Materials Science Engineering University of BonabBonab***Iran Faculty of Materials Engineering Sahand University of TechnologyTabriz51335-1996Iran

Hot compression tests were performed on AISI 321 austenitic stainless steel in the deformation temperature range of 800–1200℃ and constant strain rates of 0.001,0.01,0.1,and 1 s^(−1).Hot flow curves were used to determine the strain hardening exponent and the strain rate sensitivity exponent,and to construct the processing *** of the strain hardening exponent with strain were used to predict the microstructural evolutions during the hot *** variations were distinguished reflecting the different microstructural *** on the analysis of the strain hardening exponent versus strain curves,the microstructural evolutions were dynamic recovery,single and multiple peak dynamic recrystallization,and interactions between dynamic recrystallization and *** strain rate sensitivity variations at an applied strain of 0.8 and strain rate of 0.1 s^(−1) were compared with the microstructural *** results demonstrate the existence of a reliable correlation between the strain rate sensitivity values and evolved ***,the power dissipation map at the applied strain of 0.8 was compared with the resultant microstructures at predetermined deformation *** microstructural evolutions strongly correlated to the power dissipation ratio,and dynamic recrystallization occurred completely at lower power dissipation ratios.

关键词： strain hardening strain rate sensitivity processing map AISI 321 austenitic stainless steel hot compression

Layer Thickness-Dependent Hardness and strain rate sensitivity of Cu–Al/Al Nanostructured Multilayers

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Acta Metallurgica Sinica(English Letters) 2016年第2期29卷 156-162页

作者： Ya-Qiang Wang Zhao-Qi Hou Jin-Yu Zhang Xiao-Qing Liang Gang Liu Guo-Jun Zhang Jun Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University School of Materials Science and Engineering Xi’an University of Technology

Cu-Al/Al nanostructured metallic multilayers with Al layer thickness hAl varying from 5 to 100 nm were prepared, and their mechanical properties and deformation behaviors were studied by nanoindentation testing. The results showed that the hardness increased drastically with decreasing hAl down to about 20 nm, whereafter the hardness reached a plateau that approaches the hardness of the alloyed Cu-Al monolithic thin films. The strain rate sensitivity （SRS, m）, however, decreased monotonically with reducing hAl. The layer thickness-dependent strengthening mechanisms were discussed, and it was revealed that the alloyed Cu-Al nanolayers dominated at hAl≤ 20 nm, while the crystalline Al nanolayers dominated at hAl 〉 20 nm. The plastic deformation was mainly related to the ductile Al nanolayers, which was responsible for the monotonic evolution of SRS with hAl. In addition, the hAFdependent hardness and SRS were quanti- tatively modeled in light of the strengthening mechanisms at different length scales.

关键词： Nanostructured films Cu-Al/Al multilayers Hardness strain rate sensitivity Layer thickness dependence

Compressive deformation behavior of AZ31 magnesium alloy under quasi-static and dynamic loading

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Transactions of Nonferrous Metals Society of China 2010年第7期20卷 1316-1320页

作者：赵峰李玉龙索涛黄卫东刘建睿 School of Aeronautics Northwestern Polytechnical University State Key Laboratory of Solidification Processing Northwestern Polytechnical University

Compressive properties of AZ31 alloy were investigated at temperatures from room temperature to 543 K and at strain rates from 10-3to 2×10 *** results show that the compressive behavior and deformation mechanism of AZ31 depend largely on the temperature and strain *** flow stress increases with the increase of strain rate at fixed temperature,while decreases with the increase of deformation temperature at fixed strain *** low temperature and quasi-static condition,the true stress-true strain curve of AZ31 alloy can be divided into three stages(strain hardening,softening and stabilization) after ***,at high temperature and high strain rate,the AZ31 alloy shows ideal elastic-plastic *** is therefore suggested that the change in loading conditions(temperature and strain rate) plays an important role in deformation mechanisms of AZ31 alloy.

关键词： AZ3 lmagnesium alloy compressive properties dynamic deformation strain hardening strain rate sensitivity