Effect Of Grain Size Research Articles

Influence of prior austenite grain structure on hydrogen-induced fracture in as-quenched martensitic steels

Suppressing hydrogen embrittlement in martensitic steels is a longstanding challenge. Here, we studied the effects of prior austenite grain (PAG) shape and size with a 0.25C steel utilising novelin situH-charging, constant-displacement Tuning-fork testing (TFT) and H-permeation tests. Anisotropic elongated PAG structure has enhanced HE resistance transverse to the rolling direction (RD) with slower crack propagation rate (CPR) and quasi-cleavage fracture. Larger elongated grains are prone to intergranular fracture when crack propagates in RD. Reaustenitised equiaxed PAGs fail with intergranular cracking, which accelerates max CPR up to threefold compared to quasi-cleavage. All the microstructures have similar H-diffusion ∼5 × 10−7 cm2/s and density of reversible H-traps NT ∼ 3 × 1016, irrespective of PAG surface area, indicating that PAG boundaries are not effective diffusion paths. Deformed PAG boundaries mitigate susceptibility to intergranular cracking.

Comprehensive effect of grain size and original target morphology on sputtering behavior of magnetron sputtering target

In this paper, the etching morphology, surface roughness, target voltage, and light emission line intensity of the copper target were investigated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The results show that the morphology of the sputtering zone, the target voltage value, the surface roughness, and the OEM value are significantly correlated with the grain size of the target. After sputtering, the original target's morphology dramatically influences the surface roughness and OEM value.

Dependence of grain size on grain boundary diffusion mechanism of Nd-Fe-B sintered magnets

The methods to improve the grain boundary diffusion efficiency of Nd-Fe-B magnets are mostly focused on the type of diffusion source and the preparation method, while the characteristics of the diffusion matrix are less studied. In this paper, the effect of grain size in diffusion matrix on the grain boundary diffusion mechanism of Tb element is investigated intensively. The results show that with only 0.75 wt. % TbF3 diffusion, the intrinsic coercivity increases by 8.83 kOe for the magnet with finer average grain size, while the increase for coarse-grain magnet is only about 6.99 kOe. The huge increase in the intrinsic coercivity is attributed to the increase in the defect density inside the magnet due to the grain refinement. More defects lead to a reduction in diffusion activation energy and thus an increase in diffusion efficiency. The grain refinement also leads to higher grain orientation. This facilitates a smooth and uniform diffusion of the heavy rare earth elements into deeper regions to form a highly uniform shell structure. In this work, starting from the characteristics of diffusion matrix factors, it is found that the grain refinement is beneficial for the diffusion of heavy rare earth elements, which provides a novel idea for improving the grain boundary diffusion efficiency and magnetic properties.

Novel effects of grain size and ion implantation on grain boundary segregation in ion irradiated austenitic steel

Nuclear reactor environments are extreme in nature due to the combination of exposure to corrosive coolant, mechanical stresses, and neutron irradiation damage. This combination of environments can lead to irradiation induced/assisted precipitation, segregation, and embrittlement coupled with enhanced creep and stress corrosion cracking. While nanostructured materials are of interest in a variety of applications due to their unique properties including high mechanical strength, for nuclear applications nanostructured materials have the added benefit of irradiation resistance due to the high volume density of sinks for irradiation-induced defects. In this study, we show unique radiation-induced segregation (RIS) behavior in nanocrystalline 304 stainless steel (SS304). Typical RIS in austenitic steels includes Ni enrichment and Cr depletion within the grain boundaries. In nanostructured SS304 this RIS is reduced. Furthermore, interestingly, some grain boundaries in the nanocrystalline SS304 in this study were found to be enriched in Cr after Fe2+ ion irradiation at 500 °C up to 50 displacements per atom (dpa). To understand this unique observation, lattice-based atomic kinetic Monte Carlo simulations were performed to investigate the effects of grain size, thermal segregation, as well as injected interstitials (introduced as Fe self-ions). The results indicate that the Cr enrichment at grain boundaries may be caused by combined effects of grain size, self-ion injection and preferential Cr diffusion via the interstitial mechanism. The findings also suggest a possible difference in RIS between ion and neutron irradiations.

Evaluation of the Influence of Grain Sizes of Nanostructured WO3 Ceramics on the Resistance to Radiation-Induced Softening.

The main purpose of this study is to test a hypothesis about the effect of grain size on the resistance to destruction and changes in the strength and mechanical properties of oxide ceramics subjected to irradiation. WO3 powders were chosen as objects of study, which have a number of unique properties that meet the requirements for their use as a basis for inert matrices of dispersed nuclear fuel. The grain-size variation in WO3 ceramics was investigated by mechanochemical grinding of powders with different grinding speeds. Grinding conditions were experimentally selected to obtain powders with a high degree of size homogeneity, which were used for further research. During evaluation of the strength properties, it was found that a decrease in the grain size leads to an increase in the crack resistance, as well as the hardness of ceramics. The increase in strength properties can be explained by an increase in the dislocation density and the volume contribution of grain boundaries, which lead to hardening and an increase in resistance. During determination of the radiation damage resistance, it was found that a decrease in grain size to 50-70 nm leads to a decrease in the degree of radiation damage and the preservation of the resistance of irradiated ceramics to destruction and cracking.

Tensile and compressive mechanical properties of nanocrystalline calcite with grain size effect

Abstract Calcite is one of the most main components of microbially induced calcium carbonate precipitation (MICP). With the in-depth research of MICP, the mechanical properties of nanocrystalline calcite attract much attention. In this paper, the deformation and failure behaviors of nanocrystalline calcite under a uniaxial tensile or compressive condition are studied by molecular dynamics simulation, and then the dominant deformation and failure mechanisms, as well as their grain size effect, are analyzed. The results show that the grain boundary densification dominates the elastic deformation, while the intragranular phase transition dominates the plastic deformation. Compared with single-crystal calcite, the elastic modulus of nanocrystalline calcite is significantly reduced and its ultimate strength is decreased by more than 50%. Nanocrystalline calcite has stronger plastic deformation ability in compression than in tension. Its tensile and compressive elastic moduli and peak stresses all increase with the average grain size. The effects of grain size on the limit stresses can be described by the inverse Hall–Petch equation. This study is helpful for tailoring the mechanical properties of MICP by the morphology of nanocrystalline calcite.

Surface modification of alloys by high-energy pulsed particle beams

The effect of particle beams on the surface of alloys is often used to obtain a material with desired characteristics. Mathematical modeling of such surface modification leads to the study of diffusion in the presence of an intense external source of diffusant. In this case peculiarities in material structure may be of great importance. A special role belongs to inter-grain boundaries in metals, the vicinities of which are regions of accelerated diffusion. Moreover, if the surface treatment by particle beam is carried out with short impulses comparable with relaxation times of diffusion and chemical processes to their equilibrium course, it may be necessary to explicitly consider the particle transfer rate in the material, for example, using the non-classical laws.In this paper we discuss the model of the treatment process by particle beam, which takes into account both the feature of grain boundary diffusion and finiteness of relaxation times of diffusion fluxes in the boundaries and in the volumes of grains. The problem is considered in two-dimensional formulation. The grains and their boundaries are treated as separate phases with different diffusion properties. The grains are represented in the form of rectangles, located at equal distances from each other. The relative size of the boundary phase may vary. Using generalized equations for diffusion fluxes with finite time of relaxation, we come to diffusion equations of hyperbolic type for the volume and the grain-boundary phases. It is assumed that between the diffusant and the treated material a summary chemical reaction occurs with formation of a summary product. A numerical study allowed us for the first time to establish the features of grain-boundary diffusion and to study the dynamics of reaction product formation for treatment times comparable to relaxation times. The effect of pulse duration and grain size on the diffusant concentration distribution for these conditions was investigated.

Dynamic thermomechanical response and constitutive modeling of eutectic high-entropy alloy

Since the eutectic high-entropy alloys (EHEAs) have been expected to be candidates for superalloys at the beginning of their invention, getting insights into their high-temperature mechanical performance under impact loadings is of particular significance for exploring their application potential in extreme service environments with high temperature and high strain rate. Meanwhile, additive manufacturing methods have been found to be very suitable for preparing EHEAs in the past two or three years. Therefore, this work, as the first attempt, carries out a comparative study on the microstructural and dynamic thermomechanical performances of the Ni32Co30Cr10Fe10Al18 (Ni32Al18) EHEA manufactured by the laser metal deposition (LMD) and arc melting. The uniaxial compressive responses are tested over a strain rate range of 0.001/s∼7000/s and a temperature range of 77 K∼1123 K. The difference in microstructures and plastic flow behaviors between the LMD and the arc melted samples are revealed. The results show that the LMD samples feature a combination of the primary FCC phases and the typical lamellar eutectic structures, while the arc melted samples possess only ultrafine lamellar eutectic structures. The LMD samples exhibit lower strength and higher ductility than the arc melted ones. The high strength in the arc melted samples is attributed to the high athermal resistance of the dense lamellar structures (composed of ultrafine FCC and B2 phases) to mobile dislocations, while the primary FCC phases lead to high ductility and strain hardening ability in the LMD samples. The anisotropy in flow stress of the LMD sample is found at each strain rate and attributed to the different phase boundary densities generated by the LMD route in different directions. Then, a viscoplastic constitutive model considering the microstructural features is developed, which can reflect the size effect of grains and phases on flow stress, as well as the influence of the phase content on the rate-temperature coupling effect. This model is demonstrated to successfully predict the dynamic plastic flow behavior of both the LMD and arc melted Ni32Al18 EHEA over a wide range of temperature. Furthermore, the Ni32Al18 EHEA is found to have superior high-temperature dynamic specific yield strength compared to several existing typical superalloys.

Effect of Grain Sizes on Electrically Assisted Micro—Filling of SUS304 Stainless Steel: Experiment and Simulation

The filling quality of micro-feature structures has a significant impact on the forming quality of micro-channels. The electrical-assisted forming technology can effectively improve the formability of difficult-to-deform materials. In this research, the electrically driven micro-compression constitutive model of SUS304 stainless steels was established to assign grain boundary and grain interior with different material properties. An electrical–thermal–mechanical coupling model was constructed to simulate the filling process considering the effect of grain boundary and grain size. Compared to the experimental results, the simulation indicated a good agreement in microstructure characteristics and higher filling height for the fine-grained material. The increase in grain boundary density makes the resistivity of the fine grain material larger, causing the current destiny and temperature of the specimen to increase with the decrease in grain size. An ellipsoidal gradient temperature distribution is observed due to the uneven current density. Because of the high geometric dislocation density near the grain boundary, a significant dislocation pile-up causes stress to concentrate. It is observed that the deformation coordination is enhanced between the grain boundary and grain core with the decrease in grain size, thus improving the material formability and forming quality.

Effects of different gasification biochar grain size on greenhouse gases and ammonia emissions in municipal aerated composting processes

This work is aimed at investigating the effects derived from the application of minimum amounts of two different sized biochars, obtained through biomass gasification, on the greenhouse gases and ammonia emissions from a co-composting process of the organic fraction of municipal solid waste. The chosen biochar-to-organic waste share is set to 3% w/w dry, and the results obtained are compared with a conventional composting process without biochar. Nine aerated static pilot-scale bins with a volume of 1.3 m3 were prototyped and run, three per thesis and three for the control. The trial lasted 63 days, following the same approach used in full-scale composting facilities. The testing period was divided into a forced aeration phase followed by a static phase. In terms of global warming potential, the use of fine biochar and coarse biochar resulted in 13 and 11 kg CO2eq ton-1 emitted respectively. These values are 36% and 45% lower than the 20 kg of CO2eq ton-1 emitted by the control theses. Specifically, the chosen minimum amounts of biochar produced a reduction of CH4 and N2O, while a significant reduction in NH3 emissions was not detected. Carbon dioxide showed a slight increase in biochar theses. This work has proven that fine and coarse gasification-derived biochars improve the bio-oxidative phenomena and reduce greenhouse gases emissions of the composters, regardless of the biochar particle size and regardless of the modest 3% w/w biochar-to-organic waste share used.

Heteroatoms co-doped carbon from biowaste for capacitive energy storage: Dependence of physicochemical properties and electrochemical performances on precursor grain sizes

Biomass wastes are widely used as precursors for synthesizing heteroatoms doped carbons for capacitive energy storage. Based on one step of carbonization and chemical etching strategy, the effect of precursor grain sizes on physicochemical properties and electrochemical performances of resulting carbons is not paid enough attention. A biowaste of macadamia nutshell with different grain sizes is employed for the synthesis of heteroatom-doped porous carbons by chemical etching in the present study. Benefiting from more pore-forming agents loaded on the precursor with smaller grain sizes, the specific surface area and specific capacitance of carbons are significantly controlled by the grain size. As the nutshell decreased from 200 to 75 μm and was treated at 700 °C, the specific surface area enlarged from 717 to 1989 m2 g−1, while the total content of heteroatoms including oxygen, nitrogen, sulfur, and phosphorus decreased from 12.4 to 9.8 at.%. In a three-electrode system, the specific capacitance of the corresponding carbon increased from 231 to 291 F g−1 at 1 A g−1. The assembled analog supercapacitor achieves a maximum specific energy of 7.8 Wh kg−1 at the specific power of 239 W kg−1 in an aqueous electrolyte. Results demonstrate smaller precursor grain sizes lead to a higher specific surface area of carbons via one step of carbonization and chemical etching, thus achieving a stronger capacitance storage capacity of supercapacitors.

RELATION BETWEEN DISCONTINUOUS PLASTIC FLOW AND STRAIN HARDENING OF THE LOW-CARBON STEEL

Purpose. Determination of the conditions for the disappearance of a section of intermittent flow and its effect on the strain hardening of low-carbon steel.
 Actuality. The use of low carbon steels with intermittent flow for stamping has a significant limitation. Based on this, the issues of the effect of ferrite grain size on the occurrence of intermittent flow are relevant for determining the optimal structural state of steels intended for deep drawing.
 Research methods. The structure of the samples was studied under a light microscope, the grain size of the ferrite was determined by the methods of quantitative metallography. The mechanical properties of steel were determined in tension at room temperature and a strain rate of 10-3 s-1. The characteristics of the initiation of plastic flow and the parameters of strain hardening were determined from the analysis of tension curves in logarithmic coordinates. In the region of uniform strain hardening, the deformation of the violation of the directly proportional relation lgσ-lgε was determined as the moment of formation of dislocation structures with a certain periodicity.
 Results. An increase in the grain size of ferrite is accompanied by a decrease in the region of intermittent flow and a shift in the moment of formation of a dislocation cellular structure towards small plastic deformations. The strain hardening rate in the region of uniform work hardening and the Lüders strain are related by an inversely proportional relationship. With excessively large grain sizes of ferrite, the difficulty of maintaining conditions for a uniform distribution of slip lines is one of the reasons for the disappearance of the intermittent flow region on the deformation curves of low-carbon steel.
 Scientific novelty. With an increase in the grain size of ferrite, the deformation of the beginning of the decay of a uniform distribution of dislocations into periodic structures is shifted to a decrease. At the same time, an increase in the ability of the metal to work hardening during the formation of a deformation band contributes to a decrease in the length of the intermittent flow section.
 Practical value. Determining the nature of the influence of the grain size of low-carbon steel ferrite on the characteristics of work hardening and the formation of dislocation periodic structures can be useful in determining the optimal structural state of steel for deep drawing.

Effect of grain size on oxidation resistance of WC-6wt%Co cemented carbide sintered by spark plasma sintering

In this study, two WC-6wt%Co cemented carbides of different fine grades were prepared via spark plasma sintering, and the average WC grain sizes in prepared WC/Co cemented carbides were 320.9 nm (ultrafine-grain) and 847.2 nm (fine-grain), respectively. The effect of grain size on the oxidation resistance of cemented carbide in the air at 600–800 °C was investigated. The results show that when the oxidation temperature is relatively low (600, 700 °C), grain refinement leads to an increase in the number of grain boundaries in the sample, which induce the formation of more fine cracks and pores in the oxide layer and adversely affect the oxidation resistance of ultrafine-grained (320.9 nm) cemented carbide. However, as the oxidation temperature increases to 800 °C, the antioxidant performance of the fine-grained (847.2 nm) cemented carbide decreases and is lower than that of the ultrafine-grained (320.9 nm) cemented carbide, with larger intergranular fracture and disintegration behavior of the oxide grains within the oxide layer being the main reasons for the deterioration of the antioxidant performance of the sample. In addition, the oxidation thermodynamics of WC/Co cemented carbide was discussed, and the macroscopic color inconsistency of the two samples was observed and explained. The apparent activation energies of WC-6wt%Co cemented carbides at 600–800 °C are calculated to be 162.78 kJ/mol and 229.69 kJ/mol, respectively for ultrafine- and fine-grained samples.

Effects of soil grain size and solution chemistry on the transport of biochar nanoparticles

Biochar nanoparticles (BC-NP) have attracted significant attention because of their unique environmental behavior, some of which could potentially limit large-scale field application of biochar. Accurate prediction of the fate and transportability of BC-NP in soil matrix is the key to evaluating their environmental influence. This study investigated the effects of soil grain size and environmentally relevant solution chemistry, such as ionic strength (cation concentration, 0.1 mM–50 mM; cation type, Na+, and Ca2+), and humic acid (HA; 0–10 mg/L), on the transport behavior of BC-NP via systematic column experiments. The transportability of BC-NP in the soil-packed column decreased with decreasing soil grain size and was inversely proportional to soil clay content. At low cation concentrations (0.1–1.0 mM), a considerable proportion of BC-NP (15.95%–67.17%) penetrated the soil columns. Compared with Na+, Ca2+ inhibited the transportability of BC-NP in the soil through a charge shielding effect. With increasing HA concentration, the transportability of BC-NP increased, likely due to an enhanced repulsion force between BC-NP and soil particles. However, at a high HA concentration (10 mg/L), Ca2+ bridging reduced the transportability of BC-NP in the soil. Breakthrough curves of BC-NP were explained by the two-site kinetic retention model. The antagonistic effects of ionic strength and HA indicated that the transport behavior of BC-NP in the soil was governed by competitive effects of some environmental factors, including soil grain size, environmental solution chemistry, and natural organic matter content.

Effect of grain size on oxidation behaviour of Ag-20Cu-30Cr alloys in 0.1 MPa pure O2 at 700 and 800 °C

Abstract Bulk three-phase nanocrystalline (NC) Ag-20Cu-30Cr alloy was obtained by hot-pressing mechanically alloyed powders, and oxidation tests were completed in 0.1 MPa pure O2 at 700 and 800 °C. The oxidation behaviour of the alloy and the effect of the grain size were also studied in comparison with the previous coarse-grained (CG) Ag-20Cu-30Cr alloy prepared by a powder metallurgy route. At the two temperatures the oxidation kinetic curves of the NC Ag-20Cu-30Cr alloy are composed of three parabolic stages, and their parabolic rate constants become smaller as the oxidation time increases. The oxidation rate at 700 °C is higher before 5 h, but lower after 5 h than that at 800 °C. Furthermore, the oxidation rate of the NC Ag-20Cu-30Cr alloy is lower than that of the CG Ag-20Cu-30Cr alloy at the same temperature. Moreover, the NC Ag-20Cu-30Cr alloy forms an outer oxide layer composed of the Cu oxides and double oxides of the metallic Ag, Cu and Cr as well as an inner regular, continuous and protective chromia layer. Thus, the Ag-20Cu-30Cr alloy can complete the transition from an internal to external oxidation of the reactive component Cr, and in the end form a regular, continuous and protective chromia layer after nanocrystallization.

An explanation for the effect of Au surface finish on the quality of sintered Ag-Au joints

As an environmentally friendly interconnection material in power electronics, silver paste is widely used in gold surface finish. To explain the delamination at the Ag-Au interface and clarify the mechanism of Ag-Au interconnection, the bonding properties of sintered silver joints on different gold-plated substrates are studied. It was concluded that the effect of grain size on Ag-Au diffusion is greater than that of grain boundary type. The gold-plating layer with larger grains provides fewer grain boundaries, which inhibits the rapid diffusion of Ag atoms due to high angle grain boundaries. In addition, to investigate the effects of Au grain boundary misorientation on Ag-Au interdiffusion, molecular dynamics simulation is carried out on the sintering process. It is not found that high angle grain boundary of Au layer promotes the diffusion of Ag atoms during pre-drying. However, in the sintering stage, the MSD (mean square displacement) of Ag atoms in the substitute-model with high angle grain boundaries is about 4 times that of with low angle grain boundaries. It is proved that owing to lots of high angle grain boundaries in the gold-plated substrate, the diffusion of Ag atoms is faster in the sintering stage.

Analysis of fine grained sand and shale sedimentary characteristics in estuary based on sediment dynamics

Due to the dual effects of fluvial and tides, the tidal sand bars in estuaries have complex sedimentary characteristics and complex internal structures, making them difficult to predict and describe. In this paper, the sedimentary dynamics numerical simulation method is used to establish a tidal-controlled estuary model. The effects of tidal range and sediment grain size on tidal sand bars are simulated. The length, width, and thickness of tidal sand bars, as well as the length and thickness of the internal shale layer, are also analyzed. The results show that in the environment of a tide-controlled estuary, the tidal range has a more significant effect on tidal sand bars compared to the sediment grain size under the specific conditions used in this study. The main effect of tidal range on tidal sand bars is that the greater the tidal range, the greater the length-to-width ratio of the sandbank, and the higher the degree of sandbank development. In a tidal-controlled estuary environment, the formation and distribution of shale layer structures are also affected by tides: the length of the shale layer increases as the tidal energy increases, but the changes in the thickness are not obvious. Numerical simulations of the development and distribution of the tidal sand bars and shale layers in estuaries based on sedimentary dynamics will provide a basis for the sedimentary evolution of tide-controlled estuaries and will provide guidance for the exploration and development of tidal estuaries.

Effect of Abrasive Grain Size on the Abrasion Volume Loss of Subfossil and Recent Oak Wood in Three Characteristic Sections

Subfossil wood is a valuable and rare material often used for production of expensive furniture and decorative artistic items of unique beauty. Its mechanical and tribological properties are still being studied and are considered specific due to the particular conditions of its long-lasting formation in aqueous sediment sludge. Various elements that have been impregnated into the wood tissue over many years make the machining and grinding of this type of wood rather difficult compared to normal recent wood. The main objective of this study was to determine the influence of the abrasive grain size of sandpaper on the abrasion volume loss of recent and two subfossil oak samples in three characteristic sections (cross, radial, and tangential). The results showed that the average size of abrasive grains and the orientation of the wood structure have an influence on the abrasion volume loss of all three samples. The phenomenon of the critical size of abrasive grains was observed in all samples and on all sections. As the size of abrasive grains increased to the critical size, the abrasive volume loss of the sample increased simultaneously. The lowest abrasion volume loss was observed on recent oak. In all samples, the lowest volume loss was measured on the cross sections, and the tangential and radial sections had mutually equal values. It was also found that the increase in the size of abrasive grains to a critical value resulted in the increasing value of the absolute difference between the abrasion volume loss of the cross, radial, and tangential section samples, while the relative relations between the abrasive volume loss values of three different sections (C/R, C/T, R/T) within the same grit of sandpaper remained quite similar.

Characterization of gradient plastic deformation in gradient nanotwinned Cu

Gradient nanostructured (GNS) metals exhibit high overall extra strengths relative to their non-gradient counterparts. However, the spatial distribution of local extra strengths stemming from plastic strain gradients remains elusive. This work is focused on characterizing the gradient distribution of plastic strains in a representative GNS metal of gradient nanotwinned (GNT) Cu. Full-field strain mapping reveals the gradient distributions of lateral strains in the transverse cross section of GNT Cu samples undergoing uniaxial tensile deformation. We find that the lateral strain gradient increases but the maximum lateral strain difference decreases in GNT samples with increasing structural gradient. The latter arises because the softest layer with the lowest initial yield strength gains the largest local extra strength during tensile deformation, and vice versa. Such a gradient distribution of local extra strengths results from the combined strengthening effects of plastic strain gradient and grain size. These experimental results are used to inform a strain gradient plasticity model for revealing the gradient distributions of local extra back stresses and local extra strengths with increasing load. The coupled experimental and modeling characterization of gradient plastic deformation provides an in-depth mechanistic understanding of the spatial-temporal evolution of gradient strengthening effects in gradient nanostructures.

Effects of grain size on the electrical properties in the Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics

Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics are prepared by the conventional solid-state reaction route, and the effect of dwell time on the physical and electrical properties has been investigated. XRD patterns show that morphotropic phase boundaries exist in all BCZT ceramics. BCZT ceramics sintered at 1450 °C for 8 h exhibit the largest grain size (10.5 μm) and highest Curie temperature (T c∼93 °C). BCZT ceramics exhibit the similar relaxor properties to ideal relaxor ferroeletric. Meanwhile, the behavior of diffuse phase transition is weakened with the increase of grain sizes. The fitted activation energy reveals the dominant defects in BCZT ceramics are oxygen vacancies, and the concentration of oxygen vacancies in the region of grain boundaries is higher than that of grains.