Characterization of mechanical properties of barium titanate ceramics with different grain sizes

AbstractIn this paper, three BaTiO3 powders of various particle size distributions were obtained as a result of mechanical activation in the mixer mill. Green barium titanate pellets and cylindrical specimens were fabricated by both uniaxial and isostatic pressing methods. As a result of the application of different maximal sintering temperatures, the obtained materials were characterized by various average grain sizes: 0.8 μm, 20 μm and 31.0 μm. The basic properties of sintered pellets and cylinders were determined and the influence of materials average grain size on their Young’s modulus and compressive strength were determined through compression tests in a uniaxial testing machine, Zwick/Roell Z100. The elastic properties were similar for tested materials with a different grain size. However, the microstructure of BaTiO3 strongly influenced the compressive strength.

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Microstructure Prediction by Finite Element Analysis during Hot Rolling of Magnesium Alloy Sheets

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.661.105 ◽

2015 ◽

Vol 661 ◽

pp. 105-112

Author(s):

Yeong Maw Hwang ◽

Tso Lun Yeh

Keyword(s):

Grain Size ◽

Magnesium Alloy ◽

Optimal Conditions ◽

Compression Tests ◽

Element Analysis ◽

Grain Sizes ◽

Average Grain Size ◽

Microstructure Prediction ◽

Alloy Microstructure ◽

The Relationship

Material’s plastic deformation by hot forming processes can be used to make the materials generate dynamic recrystallization (DRX) and fine grains and accordingly products with more excellent mechanical properties, such as higher strength and larger elongation can be obtained. In this study, compression tests and water quenching are conducted to obtain the flow stress of the materials and the grain size after DRX. Through the regression analysis, prediction equations for the magnesium alloy microstructure were established. Simulations with different rolling parameters are conducted to find out the relationship between the DRX fractions or grain sizes of the rolled products and the rolling parameters. The simulation results show that rolling temperature of 400°C and thickness reduction of 50% are the optimal conditions. An average grain size of 0.204μm-0.206μm in the microstructure is obtained and the strength and formability of ZK60 magnesium alloys can be improved.

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Dielectric Properties of Barium Titanate Ceramics with Nano-Sized Domain

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.445.27 ◽

2010 ◽

Vol 445 ◽

pp. 27-30 ◽

Cited By ~ 3

Author(s):

Yoichi Kigoshi ◽

Saki Hatta ◽

Takashi Teranishi ◽

Takuya Hoshina ◽

Hiroaki Takeda ◽

...

Keyword(s):

Grain Size ◽

Barium Titanate ◽

Dipole Polarizability ◽

Ionic Polarizability ◽

Grain Sizes ◽

Conventional Sintering ◽

Rate Controlled ◽

Titanate Ceramics ◽

Sintering Method ◽

Domain Width

Barium titanate (BaTiO3) ceramics with various grain sizes from 0.7 to 13 μm on average were prepared by a conventional sintering method, a two-step sintering method and a rate controlled two-step sintering method. The permittivity of the ceramics was increased with decreasing grain size to 1.1 μm on average. However, the permittivity of the ceramics was decreased when the grain size was below 1 μm. The field emission scanning electron microscope (FE-SEM) observations revealed that the 90º domain width decreased with decreasing the grain size. By ultrawide range dielectric spectra from kHz to THz range of the BaTiO3 ceramics, the domain contribution to the permittivity was investigated. For the BaTiO3 ceramics with grain sizes over 1 μm, the dipole polarizability and the ionic polarizability were enhanced by high domain-wall density. In contrast, for the BaTiO3 ceramics with grain sizes below 1 μm, these polarizabilities were weakened.

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Production and Mechanical Properties of Nanocrystalline Intermetallics Based on TiAl3-X

MRS Proceedings ◽

10.1557/proc-791-q7.8 ◽

2003 ◽

Vol 791 ◽

Author(s):

H. A. Calderon ◽

J. C. Aguilar-Virgen ◽

F. Cruz-Gandarilla ◽

M. Umemoto

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Grain Growth ◽

High Strength ◽

Compression Tests ◽

Grain Sizes ◽

Intermetallic Materials ◽

Plasma Sintering ◽

Average Grain Size ◽

Spark Plasma

ABSTRACTProduction of intermetallic materials in the system TiAl3-X (X = Cr, Mn, Fe) has been achieved by means of mechanical milling and sintering techniques. Spark plasma sintering is used since it reduces time at high temperature and inhibits grain growth. The produced materials have grain sizes in the nano and microscale depending on the material and processing variables. The TiAl3-X alloys are formed mostly by the cubic L12 phase. The average grain size ranges between 30 and 50 nm in the as sintered condition. Aging at elevated temperature has been used to promote grain growth. Compression tests have been performed to evaluate mechanical properties as a function of temperature and grain size. In all cases yield stresses higher that 700 MPa are obtained together with a ductility that depends upon temperature and grain size. No ductility is found for the smallest grains sizes tested (30 nm) at room temperature. Above 673 K, these materials show ductility and additionally they present a quasi superplastic behavior at temperatures higher that 973 K. On the other hand ductility can also be developed in the TiAl3-X alloys by inducing grain growth via annealing. Alloys with grains sizes around 500 nm show high ductility and a large density of microcraks after deformation suggesting that the yield strenght becomes lower than the stress to propagate the cracks. In such materials, a considerably high strength is retained up to 873 K.

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Development of Al–Mg–Si alloy performance by addition of grain refiner Al–5Ti–1B alloy

Science Progress ◽

10.1177/00368504211029469 ◽

2021 ◽

Vol 104 (2) ◽

pp. 003685042110294

Author(s):

Khaled Abd El-Aziz ◽

Emad M Ahmed ◽

Abdulaziz H Alghtani ◽

Bassem F Felemban ◽

Hafiz T Ali ◽

...

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Corrosion Resistance ◽

Testing Machine ◽

Dendritic Structure ◽

Grain Refiner ◽

Corrosion Properties ◽

Average Grain Size ◽

Structural Applications ◽

Alloy Addition

Aluminum alloys are the most essential part of all shaped castings manufactured, mainly in the automotive, food industry, and structural applications. There is little consensus as to the precise relationship between grain size after grain refinement and corrosion resistance; conflicting conclusions have been published showing that reduced grain size can decrease or increase corrosion resistance. The effect of Al–5Ti–1B grain refiner (GR alloy) with different percentages on the mechanical properties and corrosion behavior of Aluminum-magnesium-silicon alloy (Al–Mg–Si) was studied. The average grain size is determined according to the E112ASTM standard. The compressive test specimens were made as per ASTM: E8/E8M-16 standard to get their compressive properties. The bulk hardness using Vickers hardness testing machine at a load of 50 g. Electrochemical corrosion tests were carried out in 3.5 % NaCl solution using Autolab Potentiostat/Galvanostat (PGSTAT 30).The grain size of the Al–Mg–Si alloy was reduced from 82 to 46 µm by the addition of GR alloy. The morphology of α-Al dendrites changes from coarse dendritic structure to fine equiaxed grains due to the addition of GR alloy and segregation of Ti, which controls the growth of primary α-Al. In addition, the mechanical properties of the Al–Mg–Si alloy were improved by GR alloy addition. GR alloy addition to Al–Mg–Si alloy produced fine-grained structure and better hardness and compressive strength. The addition of GR alloy did not reveal any marked improvements in the corrosion properties of Al–Mg–Si alloy.

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Dynamic and Quasi-Static Compressive Deformation Behaviour of Polyimide Foam at Various Elevated Temperature

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.566.158 ◽

2014 ◽

Vol 566 ◽

pp. 158-163 ◽

Cited By ~ 1

Author(s):

A. Yosimoto ◽

Hidetoshi Kobayashi ◽

Keitaro Horikawa ◽

Keiko Watanabe ◽

Kinya Ogawa

Keyword(s):

Compressive Strength ◽

Room Temperature ◽

Deformation Behaviour ◽

Testing Machine ◽

Negative Temperature ◽

Strain Rates ◽

Compression Tests ◽

Hopkinson Pressure Bar ◽

Universal Testing ◽

Pressure Bar

In order to clarify the effect of strain rate and test temperature on the compressive strength and energy absorption of polyimide foam, a series of compression tests for the polyimide foam with two different densities were carried out. By using three testing devices, i.e. universal testing machine, dropping weight machine and sprit Hopkinson pressure bar apparatus, we performed a series of compression tests at various strain rates (10-3~103s-1) and at several test temperatures in the range of room temperature to 280 ̊C. At over 100 s-1, the remarkable increase of flow stress was observed. The negative temperature dependence of strength was also observed.

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Preparation of barium titanate ceramics from amorphous fine particles of the Ba–Ti–O system and its dielectric properties

Journal of Materials Research ◽

10.1557/jmr.1995.0306 ◽

1995 ◽

Vol 10 (2) ◽

pp. 306-311 ◽

Cited By ~ 13

Author(s):

S. Wada ◽

T. Suzuki ◽

T. Noma

Keyword(s):

Dielectric Properties ◽

Barium Titanate ◽

Curie Temperature ◽

Decomposition Method ◽

Fine Particles ◽

Nitrate Solution ◽

Pressing Method ◽

Calcination Temperatures ◽

Grain Sizes ◽

Titanate Ceramics

Using titanium nitrate solution stabilized by chelation, amorphous fine particles of the Ba-Ti-O system were prepared by the mist decomposition method in air. After calcination of these particles, barium titanate ceramics were prepared using the hot uniaxial pressing method, and various properties were investigated. As a result, the grain sizes could be controlled over the range from 58 nm to 187 nm by the sintering temperatures and/or the calcination temperatures, keeping the density almost constant. Moreover, the dielectric properties of the samples showed that the relative permittivity decreased with decreasing grain size, and Curie temperature also shifted to lower temperatures in the same way. In this study, we first found that Curie temperature existed in the barium titanate ceramics with grain sizes from 58 to 147 nm.

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Grain-Size Effects on Diffuse Phase Transitions of Batio3 Ceramics Obtained by Alkoxide Precursors

MRS Proceedings ◽

10.1557/proc-346-309 ◽

1994 ◽

Vol 346 ◽

Author(s):

R. P. S. M. Lobo ◽

R. L. Moreira ◽

N. D. S. Mohallem

Keyword(s):

Grain Size ◽

Phase Transitions ◽

Barium Titanate ◽

Size Effects ◽

Sol Gel ◽

Simple Relationship ◽

Titanate Ceramics ◽

Charged Defects ◽

Alkoxide Precursors ◽

Diffuse Phase

ABSTRACTBarium titanate ceramics have been obtained by sol-gel methods. The dielectric investigations of these materials revealed the existence of diffuse ferroelectric transitions. By using a phenomenological model, we could demonstrate the existence of a simple relationship between the diffuse character of the transition and the sample grain-size. This effect has been attributed to interactions between charged defects on the grain surfaces and the spontaneous polarization of the material.

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Effect of Annealing on Nanocrystalline Structure of Nb3Sn Diffusion Layers in Composites with Internal Tin Sources

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.297-301.126 ◽

2010 ◽

Vol 297-301 ◽

pp. 126-131 ◽

Cited By ~ 2

Author(s):

E.N. Popova ◽

Vladimir V. Popov ◽

E.P. Romanov ◽

S.V. Sudareva ◽

L.V. Elohina ◽

...

Keyword(s):

Grain Size ◽

Carrying Capacity ◽

Nanocrystalline Structure ◽

Diffusion Annealing ◽

External Diameter ◽

High Temperature Annealing ◽

Grain Sizes ◽

Diffusion Layers ◽

Average Grain Size ◽

Complete Transformation

Multifilamentary Nb3Sn-based superconducting composites manufactured by an internal-tin method have been studied by transmission (TEM) and scanning (SEM) electron microscopy. The main goal of this study is to reveal the effect of diffusion annealing regimes as well as the external diameter of the wires on the structure of nanocrystalline Nb3Sn layers (average grain size, grain size distribution, layer thickness, amount of Sn, etc.). It is demonstrated that multistep diffusion annealing results in quite a complete transformation of Nb filaments into Nb3Sn though some amount of the residual Nb remains in the filaments center. With an external diameter decrease the superconducting layers structure has been found to refine and get somewhat more uniform. An additional high-temperature annealing results in marked growth of Nb3Sn grain sizes and their scattering in sizes, which may negatively affect the current-carrying capacity of a wire.

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Characterization of Defect Nucleation and Propagation in Fe2O3+FCC-Al Nanocomposites During Uniaxial Tensile and Compressive Deformations

Applied Mechanics ◽

10.1115/imece2006-13629 ◽

2006 ◽

Author(s):

Vikas Tomar ◽

Min Zhou

Keyword(s):

Molecular Dynamics ◽

Grain Size ◽

Defect Formation ◽

Voronoi Tessellation ◽

Orientation Distribution ◽

Uniaxial Tensile ◽

Grain Sizes ◽

Classical Molecular Dynamics ◽

Average Grain Size ◽

Nanocrystalline Structures

The objective of this research is to analyze uniaxial tensile and compressive mechanical deformations of α-Fe2O3 + fcc Al nanoceramic-metal composites using classical molecular dynamics (MD). Specifically, variations in the nucleation and the propagation of defects (such as dislocations and stacking faults etc.) with variation in the nanocomposite phase morphology and their effect on observed tensile and compressive strengths of the nanocomposites are analyzed. For this purpose, a classical molecular dynamics (MD) potential that includes an embedded atom method (EAM) cluster functional, a Morse type pair function, and a second order electrostatic interaction function is developed, see Tomar and Zhou (2004) and Tomar and Zhou (2006b). The nanocrystalline structures (nanocrystalline Al, nanocrystalline Fe2O3 and the nanocomposites with 40% and 60% Al by volume) with average grain sizes of 3.9 nm, 4.7 nm, and 7.2 nm are generated using a combination of the well established Voronoi tessellation method with the Inverse Monte-Carlo method to conform to prescribed log-normal grain size distributions. For comparison purposes, nanocrystalline structures with a specific average grain size have the same grain morphologies and the same grain orientation distribution. MD simulations are performed at the room temperature (300 K). Calculations show that the deformation mechanism is affected by a combination of factors including the fraction of grain boundary (GB) atoms and the electrostatic forces between atoms. The significance of each factor is dependent on the volume fractions of the Al and Fe2O3 phases. Depending on the relative orientations of the two phases at an interface, the contribution of the interface to the defect formation varies. The interfaces have stronger effect in structures with smaller average grain sizes than in structures with larger average grain sizes.

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