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Phase Field Study of Ferroelastic Toughening Mechanisms of Polycrystalline t'-YSZ 认领 引用
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作者 Zhou Fang Jiaqi Zhong +1 位作者 Jun Luo Yuanzun Sun 《Computer Modeling in Engineering & Sciences》 SCIE EI 2026年第6期110-133,共24页
The t'phase of yttria-stabilized zirconia(t'-YSZ)is the most extensively used top coat material in thermal barrier coatings(TBCs).Its relatively high fracture toughness is among the most important factors that... The t'phase of yttria-stabilized zirconia(t'-YSZ)is the most extensively used top coat material in thermal barrier coatings(TBCs).Its relatively high fracture toughness is among the most important factors that enable t'YSZ to stand out from other candidate ceramics.Unveiling the toughening mechanisms of t'-YSZ is conducive to the development of next-generation top-coat materials.In this paper,a coupled phase field model is proposed to study crack growth and domain evolution in polycrystalline t'-YSZ.Two distinct polycrystal microstructures are considered to investigate the impact of the initial domain structure on the toughening behavior.In Polycrystal I,each grain consists of a single domain of the t'phase.In Polycrystal II,the c-t'phase transformation gives rise to a twinned domain configuration.A unified phase field model is proposed to simulate the coupled process of crack propagation and domain evolution within both polycrystals.The localized toughening effect resulting from domain switching on crack advancement is characterized using the energy dissipation rate.Numerical findings reveal that the interplay between fracturing and domain evolution causes the crack to follow tortuous paths in both types of polycrystals,potentially enhancing the overall fracture toughness.The domain reorientation enhances the local crack growth resistance in both materials,though the domain evolution characteristics are distinctly different.The effects of domain evolution and the polycrystal microstructure on the crack growth behavior and the local toughening effect are systematically discussed.The findings reported in this paper offer valuable insights into the fracture toughening mechanisms of t'-YSZ ceramics.The phase field approach developed in the paper provides a powerful numerical framework for evaluating the fracture toughness of ferroelastic materials. 展开更多
关键词 Fracture toughness yttria stabilized zirconia polycrystal domain switching phase field method
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Polycrystal modeling of hot extrusion texture of AZ80 magnesium alloy 认领 引用 被引量：9
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作者 邵一川 汤韬 +3 位作者 李大永 周国伟 张少睿 彭颖红 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第4期1063-1072,共10页
The visco-plastic self-consistent (VPSC) model is extended to take the dynamical recrystallization (DRX) into account so that the hot extrusion texture of AZ80 magnesium alloy can be properly modeled. The effects of e... The visco-plastic self-consistent (VPSC) model is extended to take the dynamical recrystallization (DRX) into account so that the hot extrusion texture of AZ80 magnesium alloy can be properly modeled. The effects of extrusion temperatures and imposed boundary conditions on the resulting textures were investigated, and good agreement can be found between the simulated and the measured extrusion textures. The simulated results show that the DRX grains are responsible for the formation of the {2110} fiber component since the {1010} poles of the DRX grains are tilted away from those of the unrecrystallized grains during the formation of their high angle boundaries (HABs). Furthermore, the basal poles of the grains are favorably oriented to the transversal direction (TD) where the imposed deformation is larger due to lower slip resistance of the basal slip. The elevated temperature enhances the activity of pyramidal ?c+a? slip modes and gives rise to a larger recrystallized volume fraction, resulting in a weakened extrusion texture. 展开更多
关键词 AZ80 magnesium alloy polycrystal plasticity texture hot forward extrusion dynamic recrystallization
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Polycrystalline model for FE-simulation of micro forming processes 认领 引用 被引量：5
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作者 王春举 郭斌 单德彬 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第6期1362-1366,共5页
A new polycrystal model was presented from the viewpoint of polycrystal structure of the billets considering free surface effects.In the model,the billet was divided into three portions,such as free surface portion,tr... A new polycrystal model was presented from the viewpoint of polycrystal structure of the billets considering free surface effects.In the model,the billet was divided into three portions,such as free surface portion,transition portion and internal portion.The grains in free surface portion were considered the single grains,and the anisotropy of the grains was taken into account by introducing grain orientation to explain the inhomogeneous deformation.In the transition portion,the effects of the neighbouring grains were adopted in the model.The grains in the internal portion were considered the polycrystalline material.With the developed model,the upsetting deformation process was simulated by the MSC Superform software.The scatter of the flow stress and inhomogeneous deformation was observed by analysis of the model.The comparisons show that the computational results are good agreed with the experimental results.This means that the presented model is effective. 展开更多
关键词 micro forming size effect polycrystal model inhomogeneous deformation
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Finite element analysis using elasto-visco-plastic self-consistent polycrystal model for E-form Mg sheet subjected to bending 认领 引用 被引量：3
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作者 Bohye Jeon Min-Seong Kim +1 位作者 Shi-Hoon Choi Youngung Jeong 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第4期1393-1407,共15页
The mechanical behavior of a magnesium alloy E-form under bending was investigated using the elasto-visco-plastic polycrystal model(ΔEVPSC) and its finite element(FE) implementation(ΔEVPSC-FE) developed in Jeong et ... The mechanical behavior of a magnesium alloy E-form under bending was investigated using the elasto-visco-plastic polycrystal model(ΔEVPSC) and its finite element(FE) implementation(ΔEVPSC-FE) developed in Jeong et al. and Jeong and Tomé. The crystallographic orientation distribution(COD) obtained from X-ray diffraction was used to represent the initial texture, and the Voce hardening parameters were calibrated by fitting the uniaxial tension and the compression flow stress curves. A quasi-static FE analysis of a miniaturized V-bending operation was conducted using the ΔEVPSC-FE model. The bending induced an inhomogeneous stress response along the through-thickness and the lateral directions, which was well captured by the model. Moreover, the predictive capability of the model was validated by comparing with various experimental results such as(1) force vs. displacement curves;(2) the through-thickness variations in the twin volume fraction;and(3) the changes in crystallographic texture as a function of displacement. Additional bending simulation was performed using an isotropic texture, the result of which suggests that the potential improvement in bendability of the magnesium alloy is attainable by weakening the initial texture. Moreover, the simulation results imply that the crystallographic texture, which may affect the twin activation across the thickness direction, plays a significant role in the shifting direction of the neutral layer. 展开更多
关键词 FEM Texture V-bending Polycrystal Magnesium Elasto-visco-plasticity
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3D Crystal Plasticity Finite Element Modeling of the Tensile Deformation of Polycrystalline Ferritic Stainless Steel 认领 引用 被引量：3
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作者 Chi Zhang Li-Wen Zhang +2 位作者 Wen-Fei Shen Ying-Nan Xia Yu-Tan Yan 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2017年第1期79-88,共10页
A mesoscale model of plastic deformation of ferritic stainless steels （FSSs） is formulated by combining a crystal plasticity finite element model with 3D cellular automaton algorithm. The actual grain orientations o... A mesoscale model of plastic deformation of ferritic stainless steels （FSSs） is formulated by combining a crystal plasticity finite element model with 3D cellular automaton algorithm. The actual grain orientations of FSS cold rolling and annealing sheet have been detected by electron backscatter diffraction and selected to be assigned to the polycrystal model. The simulation results have been validated by comparing the calculated true stress-strain response with the experimental one. For the lack of considering the interactions of dislocations with impurities, there are no upper and lower yield points in the simulation stress-strain curves. However, the calculated yield strength and the stress-strain response after yielding agree well with the real material. The local stress and strain fields show inhomogeneous at mesoscale. The plastic deformations of the grains with typical orientations have been characterized. The analysis reveals that the grains with fiber texture show higher thickness reduction ratio as compared to others. The deformation behaviors of the grains in polycrystal are not only related to the orientations but also to the interactions from adjacent grains. 展开更多
关键词 Ferritic steels Crystallographic orientation Polycrystal plasticity modeling Cellular automaton
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PREDICTION OF YIELD FUNCTIONS ON BCC POLYCRYSTALS 认领 引用 被引量：5
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作者 Huang Mojia Fu Mingfu Zheng Chaomei 《Acta Mechanica Solida Sinica》 SCIE EI 2006年第1期75-85,共11页
By the nonlinear optimization theory, we predict the yield function of single BCC crystals in Hill＇s criterion form. Then we give a formula on the macroscopic yield function of a BCC polycrystal Ω under Sachs＇ mode... By the nonlinear optimization theory, we predict the yield function of single BCC crystals in Hill＇s criterion form. Then we give a formula on the macroscopic yield function of a BCC polycrystal Ω under Sachs＇ model, where the volume average of the yield functions of all BCC crystallites in Ω is taken as the macroscopic yield function of the BCC polycrystal. In constructing the formula, we try to find the relationship among the macroscopic yield function, the orientation distribution function （ODF）, and the single BCC crystal＇s plasticity. An expression for the yield stress of a uniaxial tensile problem is derived under Taylor＇s model in order to compare the expression with that of the macroscopic yield function. 展开更多
关键词 yield function the ODF BCC polycrystal single BCC crystals anisotropy
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Force-Field Derivation and Atomistic Simulation of HMX/Graphite Interface and Polycrystal Systems 认领 引用 被引量：3
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作者 LONG Yao LIU Yong-Gang +1 位作者 NIE Fu-De CHEN Jun 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第1期102-114,共13页
Interface is the key issue to understand the performance of composite materials.In this work,we study the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) and graphite,try to find out its contri... Interface is the key issue to understand the performance of composite materials.In this work,we study the interface between octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) and graphite,try to find out its contribution to mixture explosives.The work starts from the force-field derivation.We get ab initio based pair potentials across the interface,and then use them to study the interface structural and mechanical properties.A series of large scale molecular dynamics simulations are performed.The structure evolution,energy variation and elastic/plastic transformation of interface and polycrystal systems are calculated.The desensitizing mechanism of graphite to HMX is discussed. 展开更多
关键词 graphite-coated HMX interracial potentials tensile test polycrystal
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CYCLIC HARDENING BEHAVIOR OF POLYCRYSTALS WITH PENETRABLE GRAIN BOUNDARIES:TWO-DIMENSIONAL DISCRETE DISLOCATION DYNAMICS SIMULATION 认领 引用 被引量：3
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作者 Chuantao Hou Zhenhuan Li +1 位作者 Minsheng Huang Chaojun Ouyang 《Acta Mechanica Solida Sinica》 SCIE EI 2009年第4期295-306,共12页
A two-dimensional discrete dislocation dynamics(DDD)technology by Giessen and Needleman(1995),which has been extended by integrating a dislocation-grain boundary interaction model,is used to computationally analyze th... A two-dimensional discrete dislocation dynamics(DDD)technology by Giessen and Needleman(1995),which has been extended by integrating a dislocation-grain boundary interaction model,is used to computationally analyze the micro-cyclic plastic response of polycrystals containing micron-sized grains,with special attentions to significant influence of dislocationpenetrable grain boundaries(GBs)on the micro-plastic cyclic responses of polycrystals and underlying dislocation mechanism.Toward this end,a typical polycrystalline rectangular specimen under simple tension-compression loading is considered.Results show that,with the increase of cycle accumulative strain,continual dislocation accumulation and enhanced dislocation-dislocation interactions induce the cyclic hardening behavior;however,when a dynamic balance among dislocation nucleation,penetration through GB and dislocation annihilation is approximately established,cyclic stress gradually tends to saturate.In addition,other factors,including the grain size,cyclic strain amplitude and its history,also have considerable influences on the cyclic hardening and saturation. 展开更多
关键词 discrete dislocation dynamics simulation cyclic micro-plasticity size effect polycrystals grain boundary penetrability
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Constitutive relation of an orthorhombic polycrystal with the shape coefficients 认领 引用 被引量：10
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作者 Mojia Huang Zhiwen Lan Huiling Liang 《Acta Mechanica Sinica》 SCIE EI CAS 2005年第6期608-618,共11页
An orthorhombic polycrystal is an orthorhombic aggregate of tiny crystallites. In this paper, we study the effect of the crystalline mean shape on the constitutive relation of the orthorhombic polycrystal. The crystal... An orthorhombic polycrystal is an orthorhombic aggregate of tiny crystallites. In this paper, we study the effect of the crystalline mean shape on the constitutive relation of the orthorhombic polycrystal. The crystalline mean shape and the crystalline orientation arrangement are described by the crystalline shape function （CSF） and the orientation distribution function （ODF）, respectively. The CSF and the ODF are expanded as an infinite series in terms of the Wigner D-functions. The expanded coefficients of the CSF and the ODF are called the shape coefficients s^lm0 and the texture coefficients c^lmn respectively. Assuming that Ceff in the constitutive relation depends on the shape coefficients s^lm0 and the texture coefficients c^lmn by the principle of material frame-indifference we derive an analytical expression for C^eff up to terms linear in s^lmo and c^lmn and the expression would be applicable to the polycrystal whose texture is weak and whose crystalline mean shape has weak anisotropy. C^cff contains six unspecified material constants （λ, μ, c, s1, s2, s3）, five shape coefficients （s^2 00, s^2 20, s^4 00, s^4 20, s^4 40）, and three texture coefficients （c^4 99,c^4 20, c^4 40）, The results based on the perturbation approach are used to determine the five material constants approximately. We also find that the shape coefficients 2 and a s^2mo and s^4m0 are all zero if the crystalline mean shape is a cuboid. Some examples are given to compare our computational results. 展开更多
关键词 Crystalline mean shape Constitutive relation Orthorhombic polycrystal The shape coefficients The texture coefficients
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Giant Magnetostrictions of Tb-Dy-Fe Polycrystals with < 110 > Axial Alignment 认领 引用 被引量：6
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作者 Shouzeng ZHOU, Xuexu GAO, Maocai ZHANG, Qing ZHAO and Zhenhlla SHI 《Journal of Materials Science & Technology》 SCIE EI CAS 2000年第2期175-176,共2页
Preparing method and processing of Tb-Dy-Fe alloy samples with [110] axial orientation as well as their magnetostrictive properties have been studied. It has been found that the magnetostrictive strains of polycrystal... Preparing method and processing of Tb-Dy-Fe alloy samples with [110] axial orientation as well as their magnetostrictive properties have been studied. It has been found that the magnetostrictive strains of polycrystal samples with [110] axial orientation can reach (1550-1900) ×10~-6 in a low magnetic field less than 80 kA/m, which are equal to or somewhat better than that of the polycrystal samples with [112] axial orientation. 展开更多
关键词 110 Giant Magnetostrictions of Tb-Dy-Fe Polycrystals with Axial Alignment Fe Dy
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Experimental Study and Finite Element Polycrystal Model Simulation of the Cold Rolling Textures in a Powder Metallurgy Processed Pure Aluminum Plate 认领 引用 被引量：4
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作者 LiqingCHEN NaoyukiKanetake 《Journal of Materials Science & Technology》 SCIE EI CAS 2005年第2期148-154,共7页
Ingot metallurgy (IM) aluminum has long been the subject and attracted the attention of many metallurgists and textural researchers of materials. Due to the introduction of large amounts of ex situ interfaces, however... Ingot metallurgy (IM) aluminum has long been the subject and attracted the attention of many metallurgists and textural researchers of materials. Due to the introduction of large amounts of ex situ interfaces, however, the textures in powder metallurgy (PM) processed aluminum has been rarely reported. In this article, a pure aluminum plate was prepared via PM route. The starting billet was first produced with uni-axially cold compaction and flat hot-extrusion and then followed by cold rolling processes. The hot-extruded and cold rolling deformation textures of the pure PM aluminum at 50%, 80% and 90% cold rolling reductions were studied by orientation distribution functions (ODFs) analysis. The finite element polycrystal model (FEPM) was finally utilized to simulate the cold rolling textural evolution at various stages of cold rolling. In FEPM simulation, the initial hot-extruded textures were taken into account as inputs. The results showed that typical β-fiber texture formed in pure PM aluminum with the cold rolling reduction increased till 80%, and there was not much change after excessive cold rolling deformation. Homogeneous slip is not the only deformation mode in PM processed pure aluminum plate at over 80% cold rolling reduction. The experimental results were qualitatively in good agreement with the simulated ones. 展开更多
关键词 Texture Cold rolling Aluminium Finite element polycrystal model (FEPM) Powder metallurgy
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CRACK PROPAGATION IN POLYCRYSTALLINE ELASTIC-VISCOPLASTIC MATERIALS USING COHESIVE ZONE MODELS 认领 引用 被引量：1
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作者 吴艳青 张克实 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第4期509-518,共10页
Cohesive zone model was used to simulate two-dimensional plane strain crack propagation at the grain level model including grain boundary zones. Simulated results show that the original crack-tip may not be separated ... Cohesive zone model was used to simulate two-dimensional plane strain crack propagation at the grain level model including grain boundary zones. Simulated results show that the original crack-tip may not be separated firstly in an elastic-viscoplastic polycrystals. The grain interior＇s material properties （e.g. strain rate sensitivity） characterize the competitions between plastic and cohesive energy dissipation mechanisms. The higher the strain rate sensitivity is, the larger amount of the external work is transformed into plastic dissipation energy than into cohesive energy, which delays the cohesive zone rupturing. With the strain rate sensitivity decreased, the material property tends to approach the elastic-plastic responses. In this case, the plastic dissipation energy decreases and the cohesive dissipation energy increases which accelerates the cohesive zones debonding. Increasing the cohesive strength or the critical separation displacement will reduce the stress triaxiality at grain interiors and grain boundaries. Enhancing the cohesive zones ductility can improve the matrix materials resistance to void damage. 展开更多
关键词 crack propagation elasto-viscoplastic cohesive zone： model polycrystal grain boundary
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A micromechanics-based finite element model for the constitutive behavior of polycrystalline ferromagnets 认领 引用 被引量：2
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作者 Binglei Wang Changqing Chen Yapeng Shen 《Acta Mechanica Sinica》 SCIE EI CAS 2006年第3期257-264,共8页
A micromechanics-based finite element model for the constitutive behavior of polycrystalline ferromagnets is developed. In the model, the polycrystalline solid is assumed to comprise numerous single crystals with rand... A micromechanics-based finite element model for the constitutive behavior of polycrystalline ferromagnets is developed. In the model, the polycrystalline solid is assumed to comprise numerous single crystals with randomly distributed crystallographic orientations, and the single crystals, in turn, consist of ferromagnetic domains, each of which is represented by a cubic element. The dipole directions of the domains are randomly assigned to simulate the crystallographic nature of ferromagnetic polycrystals. A switching criterion for the domains is specified at the microscopic level. The macroscopic constitutive behavior is obtained by averaging the microscopic/local behavior of each domain. The developed model has been applied to the simulation of a ferromagnetic material. With appropriate material parameters adopted, hysteresis loops of the predicted magnetic induction versus magnetic field and those of the strain versus magnetic field are shown to agree well with experimental observations. 展开更多
关键词 Ferromagnetic polycrystal. Micromechanics Finite element Domain switching
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Constitutive relation of weakly anisotropic polycrystal with microstructure and initial stress 认领 引用 被引量：7
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作者 Mojia Huang Hua Zhan Xiuqiao Lin Hai Tang 《Acta Mechanica Sinica》 SCIE EI CAS 2007年第2期183-198,共16页
Man （Nondestr Test Eval 15：191-214, 1999） derived the constitutive relation of a weakly-textured orthorhombic aggregate of cubic crystallites with effects of microstructure and initial stress. In this paper, a comp... Man （Nondestr Test Eval 15：191-214, 1999） derived the constitutive relation of a weakly-textured orthorhombic aggregate of cubic crystallites with effects of microstructure and initial stress. In this paper, a computational expression on the integration ∫SO（3） Q^× D^1m0dg is given. Then, by means of the computational expression, the general constitutive relation of a weakly-textured anisotropic polycrystal with the consideration of microstructure and initial stress is derived. As special cases of our general constitutive relation, two constitutive relations are given for an isotropic polycrystal and a weakly-textured anisotropic aggregate of cubic crystallites. The acoustoelastic tensor of the reference cubic crystal is derived to determine the material constants of the polycrystal. Two examples are given for understanding the physical meaning of the texture coefficients and the constitutive relations. 展开更多
关键词 Generalconstitutive relation of weakly-textured polycrystal .Microstructure Initial stress .Cubic crystallites
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Hydrogen trapping and diffusion in polycrystalline nickel:The spectrum of grain boundary segregation 认领 引用
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作者 Yu Ding Haiyang Yu +4 位作者 Meichao Lin Michael Ortiz Senbo Xiao Jianying He Zhiliang Zhang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2024年第6期225-236,共12页
Hydrogen as an interstitial solute at grain boundaries(GBs)can have a catastrophic impact on the mechanical properties of many metals.Despite the global research effort,the underlying hydrogen-GB interactions in polyc... Hydrogen as an interstitial solute at grain boundaries(GBs)can have a catastrophic impact on the mechanical properties of many metals.Despite the global research effort,the underlying hydrogen-GB interactions in polycrystals remain inadequately understood.In this study,using Voronoi tessellations and atomistic simulations,we elucidate the hydrogen segregation energy spectrum at the GBs of polycrystalline nickel by exploring all the topologically favorable segregation sites.Three distinct peaks in the energy spectrum are identified,corresponding to different structural fingerprints.The first peak(-0.205 eV)represents the most favorable segregation sites at GB core,while the second and third peaks account for the sites at GB surface.By incorporating a thermodynamic model,the spectrum enables the determination of the equilibrium hydrogen concentrations at GBs,unveiling a remarkable two to three orders of magnitude increase compared to the bulk hydrogen concentration reported in experimental studies.The identified structures from the GB spectrum exhibit vastly different behaviors in hydrogen segregation and diffusion,with the low-barrier channels inside GB core contributing to short-circuit diffusion,while the high energy gaps between GB and neighboring lattice serving as on-plane diffusion barriers.Mean square displacement analysis further confirms the findings,and shows that the calculated GB diffusion coefficient is three orders of magnitude greater than that of lattice.The present study has a significant implication for practical applications since it offers a tool to bridge the gap between atomic-scale interactions and macroscopic behaviors in engineering materials. 展开更多
关键词 Hydrogen embrittlement Grain boundaries Impurity segregation Polycrystal Atomistic simulations
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Effect of Relative Grain Size on the Flow Stress of Polycrystalline FCC Sheets 认领 引用
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作者 YANG Mei DU Jitao +1 位作者 LI Houjia ZHANG Xiaoyan 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2012年第3期477-483,共7页
A dynamic explicit finite element code and rate-dependent elastic-viscoplastic polycrystalline model were used to simulate the simple tension test of annealing FCC polycrystal and 6111-T4 aluminum alloy sheet metal.Th... A dynamic explicit finite element code and rate-dependent elastic-viscoplastic polycrystalline model were used to simulate the simple tension test of annealing FCC polycrystal and 6111-T4 aluminum alloy sheet metal.The variability of flow stress was investigated,which was induced by various grain boundary constraints when the ratio of thickness-to-grain size was changed.The simulated results show that,when the relative grain size increases,the constraint of grain boundary will increase accordingly,which results in the increase of the flow stress of polycrystal.The results agree with experiments. 展开更多
关键词 micro-forming crystal plasticity polycrystal grain size
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Direction-dependent functions of physical properties for crystals and polycrystals 认领 引用
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作者 Mojia Huang Mengcheng Chen Tenglong Zheng 《Acta Mechanica Sinica》 SCIE EI CAS 2009年第5期639-649,共11页
Some physical properties of crystals differ in direction n because crystal lattices are often anisotropic. A polycrystal is an aggregate of numerous tiny crystallites. Unless the polycrystal is an isotropic aggregate ... Some physical properties of crystals differ in direction n because crystal lattices are often anisotropic. A polycrystal is an aggregate of numerous tiny crystallites. Unless the polycrystal is an isotropic aggregate of crystallites, the physical properties of the polycrystal vary with n. The direction-dependent functions （DDF） for crystals and polycrystals are introduced to describe the variations of the physical properties in direction n. Until now there are few papers dealing systematically with relations between the DDF and the crystalline orientation distribution. Herein we give general expressions of the DDF for crystals and polycrystals. We discuss the applications of the DDF in describing the physical properties of crystals and polycrystals. 展开更多
关键词 Direction-dependent function Orientation distribution function Physical properties of crystals and polycrystals
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STUDY OF POSITRON ANNIHILATION ONE DIMENSION ANGULAR-CORRELATION RADIATION ON POLYCRYSTAL Na^+ CONDUCTOR Na_5Y1-xCr_xSi_4O12 认领 引用
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作者 崔万秋 蔡飞虎 朱警生 《Journal of Wuhan University of Technology(Materials Science)》 SCIE CAS 1992年第4期11-17,共7页
With positron annihilation radiation one dimension angular-correlation device, it is measured that positron annihilation radiation one dimension angular-correlation curves of polycrystal sodium ion conductor Na5Y1-x C... With positron annihilation radiation one dimension angular-correlation device, it is measured that positron annihilation radiation one dimension angular-correlation curves of polycrystal sodium ion conductor Na5Y1-x CrxSi4O12 (NYCS) system. After electron momentum distribution curves are normalized, linear parameters are calculated. The parameters H, W and S show the change of Na+ ion vacancy concentration in NYCS series samples. The results show that parameters H, W and S of one dimension angular-correlation curves of those samples vary greatly with Cr2O3 contents. With Cr2O3 content increasing, H and S parameters increase, but W decreases, and reaches extremes at x=0.05; then with Cr2O3 adding continually, parameters H and S decrease gradually, parameter W increases gradually. This shows that, in addtion to Cr2O3, the conductivity has close relation with the concentration of Na+ ion vacancy. 展开更多
关键词 polycrystal Na+ ion conductor positron annihilation one dimension angular-correlation radiation
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Influence of Al on the magnetostriction of Fe-Ga polycrystal alloys under compressive stress 认领 引用 被引量：6
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作者 Long-long Liao Mei-ling Fang +2 位作者 Jie Zhu Ji-heng Li Jian Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第1期52-57,共6页
Fe80Ga20-xAlx （x = 0, 6, 9, 14） ingots were prepared from high purity elements using a vacuum induction system. X-ray diffraction patterns show that the alloys are A2 disordered structures. The influence of the part... Fe80Ga20-xAlx （x = 0, 6, 9, 14） ingots were prepared from high purity elements using a vacuum induction system. X-ray diffraction patterns show that the alloys are A2 disordered structures. The influence of the partial substitution of Ga in Fe-Ga alloys with A1 on their magnetostrictive properties was investigated, and the effects of different heat treatment conditions on the magnetostriction and microstructure of the alloy rods were also examined. The saturation magnetostriction value of FesoGa2o can reach to 240 x 10-6 under a compressive stress of 20 MPa. The Fe80GallA19 alloy has many good properties, such as low hysteresis, high linearity of the magnetostriction curve, and low saturated magnetic field, which make it a potential candidate for magnetostrictive actuator and transducer applications. It is found that subgrains have little influence on the magnetostriction of Fe-Ga alloys. 展开更多
关键词 iron-gallium alloys polycrystals aluminum magnetostriction compressive stress
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A Numerical Study of Localized Plastic Deformationin Polycrystals 认领 引用
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作者 Chengjiang HUANG, Dianzhong LI, Changrong CHEN and Yiyi LI Institute of Metal Research, Chinese Academy of Science, Shenyang 110015, China 《Journal of Materials Science & Technology》 SCIE EI CAS 2001年第2期211-214,共4页
A finite element formulation which derives constitutive response from crystal plasticity theory was used to examine localized deformation in fee polycrystals. The polycrystal model was an idealized planar array of 22 ... A finite element formulation which derives constitutive response from crystal plasticity theory was used to examine localized deformation in fee polycrystals. The polycrystal model was an idealized planar array of 22 hexagonal grains. The constitutive description used is based on a finite strain kinematical theory that accounts for lattice rotations. Formation of shear bands was successfully modeled in both single crystal and polycrystals. Stress and strain distribution around triple junctions was also analyzed. Results show the distributions of stresses and strains are distinctly inhomogeneous. Stress and strain fields across grain boundaries are highly discontinuous. However, this discontinuity will be restrained when shear bands are fully developed. 展开更多
关键词 A Numerical Study of Localized Plastic Deformationin Polycrystals
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