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Grain boundary

About: Grain boundary is a(n) research topic. Over the lifetime, 70126 publication(s) have been published within this topic receiving 1525995 citation(s).

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Book
01 Dec 1960-
Abstract: INTRODUCTION. Ceramic Processes and Products. CHARACTERISTICS OF CERAMIC SOLIDS. Structure of Crystals. Structure of Glasses. Structural Imperfections. Surfaces, Interfaces, and Grain Boundaries. Atom Mobility. DEVELOPMENT OF MICROSTRUCTURE IN CERAMICS. Ceramic Phase Equilibrium Diagrams. Phase Transformation, Glass Formation and Glass--Ceramics. Reactions with and between Solids. Grain Growth. Sintering and Vitrification. Microstructure of Ceramics. PROPERTIES OF CERAMICS. Thermal Properties. Optical Properties. Plastic Deformation, Viscous Flow and Creep. Elasticity, Anelasticity and Strength. Thermal and Compositional Stresses. Electrical Conductivity. Dielectric Properties. Magnetic Properties.

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6,594 citations


Journal ArticleDOI
Marc A. Meyers1, A. Mishra1, David J. Benson1Institutions (1)
Abstract: The mechanical properties of nanocrystalline materials are reviewed, with emphasis on their constitutive response and on the fundamental physical mechanisms. In a brief introduction, the most important synthesis methods are presented. A number of aspects of mechanical behavior are discussed, including the deviation from the Hall–Petch slope and possible negative slope, the effect of porosity, the difference between tensile and compressive strength, the limited ductility, the tendency for shear localization, the fatigue and creep responses. The strain-rate sensitivity of FCC metals is increased due to the decrease in activation volume in the nanocrystalline regime; for BCC metals this trend is not observed, since the activation volume is already low in the conventional polycrystalline regime. In fatigue, it seems that the S–N curves show improvement due to the increase in strength, whereas the da/dN curve shows increased growth velocity (possibly due to the smoother fracture requiring less energy to propagate). The creep results are conflicting: while some results indicate a decreased creep resistance consistent with the small grain size, other experimental results show that the creep resistance is not negatively affected. Several mechanisms that quantitatively predict the strength of nanocrystalline metals in terms of basic defects (dislocations, stacking faults, etc.) are discussed: break-up of dislocation pile-ups, core-and-mantle, grain-boundary sliding, grain-boundary dislocation emission and annihilation, grain coalescence, and gradient approach. Although this classification is broad, it incorporates the major mechanisms proposed to this date. The increased tendency for twinning, a direct consequence of the increased separation between partial dislocations, is discussed. The fracture of nanocrystalline metals consists of a mixture of ductile dimples and shear regions; the dimple size, while much smaller than that of conventional polycrystalline metals, is several times larger than the grain size. The shear regions are a direct consequence of the increased tendency of the nanocrystalline metals to undergo shear localization. The major computational approaches to the modeling of the mechanical processes in nanocrystalline metals are reviewed with emphasis on molecular dynamics simulations, which are revealing the emission of partial dislocations at grain boundaries and their annihilation after crossing them.

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3,425 citations


Journal ArticleDOI
Wanyi Nie1, Hsinhan Tsai1, Reza Asadpour2, Jean-Christophe Blancon1  +8 moreInstitutions (3)
30 Jan 2015-Science
TL;DR: A solution-based hot-casting technique is demonstrated to grow continuous, pinhole-free thin films of organometallic perovskites with millimeter-scale crystalline grains that are applicable to several other material systems plagued by polydispersity, defects, and grain boundary recombination in solution-processed thin films.

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Abstract: State-of-the-art photovoltaics use high-purity, large-area, wafer-scale single-crystalline semiconductors grown by sophisticated, high-temperature crystal growth processes. We demonstrate a solution-based hot-casting technique to grow continuous, pinhole-free thin films of organometallic perovskites with millimeter-scale crystalline grains. We fabricated planar solar cells with efficiencies approaching 18%, with little cell-to-cell variability. The devices show hysteresis-free photovoltaic response, which had been a fundamental bottleneck for the stable operation of perovskite devices. Characterization and modeling attribute the improved performance to reduced bulk defects and improved charge carrier mobility in large-grain devices. We anticipate that this technique will lead the field toward synthesis of wafer-scale crystalline perovskites, necessary for the fabrication of high-efficiency solar cells, and will be applicable to several other material systems plagued by polydispersity, defects, and grain boundary recombination in solution-processed thin films.

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2,626 citations


Journal ArticleDOI
Abstract: Below 1000°C the oxidation of nickel cannot be controlled by the diffusion of ions through the bulk crystal lattice of the pure oxide, because the measured oxidation rates are several orders of magnitude faster than would be predicted on this basis. Short-circuit diffusion through oxide grain boundaries or dislocations has usually been held responsible, but there has hitherto been no proper quantitative confirmation of this mechanism. We report measurements of the oxide scale thickness and oxide grain size as a function of time during the oxidation of high-purity nickel in the temperature range 500–800°C. All the oxidation experiments were carried out in pure oxygen at a pressure of one atmosphere. The measured parabolic oxidation rate constants have been compared with those calculated from grain boundary diffusion data obtained in our previous work, using a grain boundary diffusion model for the oxidation process. The quantitative agreement between measured and calculated oxidation rates shows c...

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2,573 citations


Journal ArticleDOI
Lei Lu1, Yongfeng Shen1, Xianhua Chen1, Lihua Qian1  +1 moreInstitutions (1)
16 Apr 2004-Science
TL;DR: Pure copper samples with a high density of nanoscale growth twins are synthesized and show a tensile strength about 10 times higher than that of conventional coarse-grained copper, while retaining an electrical conductivity comparable to that of pure copper.

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Abstract: Methods used to strengthen metals generally also cause a pronounced decrease in electrical conductivity, so that a tradeoff must be made between conductivity and mechanical strength. We synthesized pure copper samples with a high density of nanoscale growth twins. They showed a tensile strength about 10 times higher than that of conventional coarse-grained copper, while retaining an electrical conductivity comparable to that of pure copper. The ultrahigh strength originates from the effective blockage of dislocation motion by numerous coherent twin boundaries that possess an extremely low electrical resistivity, which is not the case for other types of grain boundaries.

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2,202 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2022185
20213,102
20203,124
20192,872
20182,789
20172,755

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Topic's top 5 most impactful authors

Yuichi Ikuhara

254 papers, 5.3K citations

Ruslan Z. Valiev

191 papers, 12.4K citations

Terence G. Langdon

142 papers, 8.9K citations

Boris B. Straumal

125 papers, 4.4K citations

Lasar S. Shvindlerman

119 papers, 4.1K citations