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cyclic deformation OF FACE CENTERED CUBIC CRYSTALS AND ITS DISLOCATION INTERACTION MODEL——Ⅱ.DISLOCATION INTERACTION MODEL OF cyclic deformation

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Acta Metallurgica Sinica(English Letters) 1989年第2期2卷 93-99页

作者： JIN Nengyun Shanghai Jiaotong University Jin Nengyun,Department of Materials Science,Shanghai Jiaotong University,Shanghai 200030,China.Present address:Max-Planck-Institut für Metallforschung,Institut für Physik,7000 Stuttgart 80,FRG

A dislocation interaction model has been proposed for cyclic deformation of fcc ***- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with the modes and intensities of dislocation interactions between slip systems active in the crystal; and,hence,may be predicted by the location of its tensile axis in the crystallographic *** model has successfully explained the different behaviours of double-slip crystals and multi-slip behaviours of some crystals with orientations usually con- sidered as single-slip ones.

关键词： face centered cubic crystal dislocation interaction model multi-slip cyclic deformation

cyclic deformation OF FACE CENTERED CUBIC CRYSTALS AND ITS DISLOCATION INTERACTION MODEL——Ⅰ.cyclic deformation OF COPPER CRYSTALS

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Acta Metallurgica Sinica(English Letters) 1989年第2期2卷 81-92页

作者： JIN Nengyun Shanghai Jiaotong University,Shanghai Jin Nengyun,Department of Materials Science,Shanghai Jiaotong University,Shanghai 200030,ChinaPresent address:Max-Planck-Institut für Metallforschung-Institut für Physik,Stuttgart 80,FRG

cyclic stress-strain responses and dislocation structure of copper single crystals with various tensile axes were systematically studied and compared with each *** results reveal that the evolution of microscopic dislocation configurations in a crystal and, accordingly,its macroscopic cyclic behaviours are closely related with its ***- markable secondary slip has been observed in some crystals with orientations well inside the crystallographic triangle, which are usually considered as single-slip *** cyclio behaviours and dislocation structures at saturation are similar to those of their neighbouring multi-slip *** results have constructed the experimental basis for the newly pro- posed dislocation interaction model Jor cyclic deformation of fee crystals,which will be des- cribed in the second part of this article.

关键词： Copper single crystal orientation cyclic deformation dislocation con figuration multi-slip

EFFECT OF SLIP ORIENTATION ON STRESS RESPONSE,INTERNAL FRICTION AND ULTRASONIC ATTENUATION DURING cyclic deformation IN Al SINGLE CRYSTALS

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Acta Metallurgica Sinica(English Letters) 1992年第6期5卷 471-476页

作者： XIA Yuebo ZHANG Tianyi State Key Laboratory for Fatigue and Fracture of Materials,Institute of Metal Research,Academia Sinica,Shenyang,ChinaFEI Guangtao ZHOU Xing Laboratory of Internal Friction and Defects in Solids,Institute of Solid State Physics,Academia Sinica,Hefei,China Associate Professor,Institute of Metal Research,Academia Sinica,Shenyang 110015,China Inst of Metal Research Acad Sinica Shenyang China

The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single *** results indicate that the value of cyclic stress σ,internal friction Q^(-1)and ultrasonic attenuation △α depend obviously on the slip *** are large differences in above three parameters for different slip orientation Al *** early stage of fatigue life,σ and △α increase and Q^(-1)decreases with cycles N,and △α reached maxi- mum before σ,while Q^(-1)and σ get the valley and the peak,respectively,at same cycles.

关键词： crystal orientation cyclic deformation stress response internal friction ultrasonic attenuation Al

Unique cyclic deformation behavior of a heavily alloyed Al-Si piston alloy at different temperatures

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Progress in Natural Science:Materials International 2012年第5期22卷 445-451页

作者： Guohua Zhang a,c,Bingchao Li b,Jianxin Zhang b,Zengjian Feng c,Zuoshan Wei c,Wei Cai a a School of Materials Science and Engineering,Harbin Institute of Technology,92 West Dazhi Street,P.O.Box 405,Harbin 150001,China b School of Materials Science and Engineering,Shandong University,17923 Jingshi Road,Jinan 250061,China c Shandong Binzhou Bohai Piston Co.,Ltd,569 Bohai Ershiyi Road,Binzhou 256602,China School of Materials Science and Engineering Harbin Institute of Technology 92 West Dazhi Street P.O. Box 405 Harbin 150001 China Shandong Binzhou Bohai Piston Co. Ltd 569 Bohai Ershiyi Road Binzhou 256602 China School of Materials Science and Engineering Shandong University 17923 Jingshi Road Jinan 250061 China

The cyclic deformation behavior of a near-eutectic Al-Si piston alloy with a variety of alloying elements is *** to the distinctive microstructure,the alloy exhibited various cyclic deformation characteristics at different *** double-stage cyclic hardening occurred at room temperature,while the first hardening was mainly caused by the interaction between the dislocations and the finely dispersive precipitates,and the dislocation/dislocation interaction resulted in the second *** elevated temperatures(200℃ and 350℃),the alloy mainly presented cyclic softening because of the fact that the thermally activated dislocations could bypass or shear the obstructive precipitates.

关键词： Aluminum alloy cyclic deformation Fatigue Intermetallics Dislocations

cyclic deformation behaviour of different crystallo- graphic orientation Al single crystals

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Progress in Natural Science:Materials International 1995年第5期 36-47页

作者：夏月波 China Chinese Academy of Sciences Institute of Metal Research Shenyang 110015 State Key Laboratory for Fatigue and Fracture of Materials

Low lycle fatigue tests were carried out for Al single crystals. The results indicate: (i) At initial stage of fatigue life, peak stress a, ultrasonic attenuation Δα, friction stress σf, back stress σb and energy loss ΔE increase with increasing cycles. These parameters slowly change or do not change basically with cycles in cyclic saturation, (ii) The effect of single crystal orientations is evident. σ, Δα and σb of mono-slip crystals are smaller than that of double- and multi-slip crystals and Q-1 of the former is larger than that of the two latters. Their hysteresis loop shapes exhibit difference. (iii) Surface observation using SEM shows that the space of slip bands decreases in mono-, double- and multi-slip orientation crystals sequence.

关键词： cyclic deformation internal friction ultrasonic attenuation friction stress back stress.

BAUSCHINGER EFFECT AND DISLOCATION STRUCTURE IN STAINLESS STEEL DURING cyclic deformation

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Acta Metallurgica Sinica(English Letters) 1989年第1期2卷 1-6页

作者： XIA Yuebo WANG Zhongguang DU Xiukui Institute of Metal Research,Academia Sinica,Shenyang,China XIA Yuebo,Associate Professor,Institute of Metal Research,Academia Sinica,Shenyang,China

cyclic deformation in symmetrical push-pull mode was carried out at room temperature in air using a Schenck hydropuls *** total strain amplitude which was kept constant dur- ing the test ranged from ±0.004 to±*** 0.2% offset yield stress σ_(0.2f) in tension and σ_(0.2r) in compression and peak stress σ were measured from the stress-strain hysteresis loop at various *** Bauschinger strenghth differential factor(BSDF)was then calcu- lated from σ_(0.2f) and σ_(0.2r).The energy loss △E of each cycle was determined from hysteresis loop *** parameters,BSDF,σ and △E,appear to have two distinctively different stages. The dislocation structures were observed using TEM in specimens deformed cyclically,for various *** observation shows that the dislocations pile-up mainly against grain boundaries and there exist large amount of deformation *** addition of 0.25 wt-% ni- trogen reduced the stacking fault energy of the alloy ***-slip and climb are therefore rather difficult to occur during the cyclic deformation at room temperature,and well-defined dislocation cells and walls can only be seen at the final stage of fatigue.

关键词： Bausckinger effect cyclic deformation dislocation structure

The Study of Dual-phase Steel after cyclic deformation at Various Strain Amplitudes

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Journal of Materials Science & Technology 1989年第6期5卷 415-420页

作者：孙正明王中光艾素华 Institute of Metal Research Academia Sinica Shenyang China. To whom correspondence should be addressed Institute of Metal Research Academia Sinica Shenyang China

Low cycle fatigue tests under plastic strain control were carried out with a dual-phase steel containing 23 Vol.-％ martensite. Specimens hardened rapidly at first few cycles followed by a slight softening to saturation stages when cycled at higher strain amplitudes, whereas at lower strain amplitudes the specimens presented continually hardening for a long time until saturation. TEM examination of the saturation dislocation structures show that clusters, parallel walls and cells were found at low, medium and high strain amplitude, respectively. It also has been found that the martensite/ferrite interfaces did not affect the dislocation structures signi- ficantly when a specimen was fatigued at lower strain amplitude. However, the dislocation struc- ture adjacent to the two-phase boundary is dif- ferent to some extent from that in the remote regions in the ferrite when a higher strain amplitude is applied.

关键词： cyclic deformation dual-phase steel dislocation structure

Investigation of the Micro-Mechanics of an Extruded Precipitation-Strengthened Magnesium Alloy under cyclic Loading

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Journal of Materials Science and Chemical Engineering 2024年第7期12卷 40-52页

作者： Chuhao Liu Xiaodan Zhang Huamiao Wang Yinghong Peng State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai China School of Mechanics and Engineering Science Shanghai University Shanghai China

Precipitation strengthening is a crucial microscopic mechanism for enhancing the strength of magnesium alloys. In order to elucidate the influence of precipitation on the microscopic deformation mechanisms and macroscopic mechanical response of magnesium alloys under cyclic loading conditions, we employed a crystal plasticity model to analyze the stress-strain curves, specific crystal plane diffraction intensities, and the temporal evolution of various microscopic deformation mechanisms and twinning volume fractions for an extruded magnesium alloy, AXM10304, containing coherent precipitates. The research findings indicate that precipitation does not fundamentally alter the microscopic mechanisms of this alloy. However, it hinders twinning during the compression stage, mildly promotes detwinning during the tension stage, and enhances tension secondary hardening by elevating the difficulty of activation of the prismatic slip.

关键词： cyclic deformation Magnesium Alloy In-Situ Neutron Diffraction Precipitation Strengthening Crystal Plasticity Lattice Strain Mechanism Evolution

Origin of superior low-cycle fatigue resistance of an interstitial metastable high-entropy alloy

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Journal of Materials Science & Technology 2022年第20期115卷 115-128页

作者： Seyed Amir Arsalan Shams Jae Wung Bae Jae Nam Kim Hyoung Seop Kim Taekyung Lee Chong Soo Lee Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea Department of Materials Science and Engineering Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea

In this study, the deformation behaviors and related microstructural evolutions were investigated in either monotonic or cyclic deformation modes in an interstitial metastable high-entropy alloy. These investigations aimed to reveal the mechanisms underlying the superior low-cycle fatigue(LCF) life of this alloy.A thermomechanical process was applied to induce fine-grained(FG) and coarse-grained(CG) microstructures in Fe–30Mn–10Co–10Cr–0.4C(atomic percentage) alloy. Their superior combination of strength and ductility was attributed to the appearance of deformation-induced ε-martensite and the presence of carbon. The CG alloy showed a greater volume fraction of ε-martensite than the FG alloy in the monotonic deformation mode, and vice versa in the cyclic mode. Such a disparity was interpreted in light of the back-stress effect of the relaxed γ-grain boundaries in the latter mode. Meanwhile, the γ-to-ε phase transformation under cyclic loading at low strain amplitudes(0.4%) barely led to an improved fatigue life as compared with that at higher strain amplitudes(≥ 0.55%). The high reversibility of partial dislocation motions under cyclic loading and delaying the formation of dislocation cells through the martensitic transformation could explain why the alloys investigated in this study exhibited a superior LCF life compared with high-entropy alloys reported in previous studies.

关键词： High-entropy alloy Transformation-induced plasticity Monotonic deformation cyclic deformation Low-cycle fatigue Stacking faults