Microstructure Property Relationships Research Articles

A computational micromechanics model to predict mechanical properties of porous silica aerogels

Porous silica aerogel is an ultra-low-density material with nanostructures that leads to its excellent physio-chemical properties. Considering the characteristics of the material, a micromechanical model to assess the microstructure–property relations is highly demanded. In this study, a cuboctahedron unit cell is proposed as a representative volume element of the silica aerogel to correlate with its density and compressive stress–strain curves. The backbone lattice-structure combined with the dead ends is established to represent the periodic configuration of the aerogel. It is implemented in both the numerical scheme with the finite element method and the analytical model by modifying the Gibson–Ashby model. Furthermore, the crushing behaviors of the material under large deformation are discussed in the numerical study. Due to the features of load-bearing skeletons and non-load-bearing short pillars, the compression process of the silica aerogel exhibits strong nonlinear behaviors. Overall, this computational micromechanics model is capable of accurately simulating the stress–strain curves of silica aerogels with different densities under different loading levels. This work provides a general framework to quantify the microstructure–property relations of porous silica aerogels and also other porous materials.

Investigation on uniaxial ratcheting fatigue behaviors and microstructure evolution of ultrafine-grained 6061 aluminum alloy

The motivation of the present study is to explore ratcheting-fatigue behavior and the corresponding micro-deformation mechanism of ultrafine-grained aluminum alloys 6061 (UFG AA6061) under two stress-controlled low-cycle fatigue (LCF) loading modes, i.e., mean tension stress (MTS) and mean compressive stress (MCS). The uniaxial ratcheting tests demonstrate that the fatigue-ratcheting damage of UFG AA6061 is prone to occur under MCS-LCF loading, rather than MTS-LCF loading. Detailed microstructure characterizations by Electron backscatter diffraction (EBSD) techniques under these two loading modes show that the grain aspect ratios decrease greatly and the fractions of high angle boundaries increase remarkably in the case of MCS-LCF loading. These observations are mainly ascribed to the room temperature continuous dynamic recrystallization (CDRX), in which low angle boundaries evolve into high angle grain boundaries and the formation of equiaxed grains is accelerated. In contrast, there were no obvious change in the grain aspect ratios or the fractions of high angle boundaries at MTS-LCF loading condition, while the Schmid factor of non-octahedral slip system {100} <110> increases and the texture evolve gradually. The deformation mechanism is grain boundary sliding (GBS) and grain rotation would accommodate the process of GBS. An analysis of the microstructure-properties relationship showed the superposition effect of residual shear deformation and uniaxial LCF ratcheting deformation is responsible for the CDRX at room temperature. And the occurrence of GBS is mainly caused by the activation of non-octahedral slip system.

A fully coupled thermal–microstructural–mechanical finite element process model for directed energy deposition additive manufacturing of Ti–6Al–4V

A fully coupled thermal–microstructural–mechanical finite element modelling framework is developed to investigate the distortion and residual stresses during directed energy deposition (DED) of multi-phase Ti–6Al–4V alloy. The Johnson–Cook constitutive model is used to predict the yield strength of each phase as a function of strain, strain rate and temperature where the flow stress is calculated by a linear mixing rule based on the volumetric phase fractions. A thin-walled rectangular sample is chosen as the reference geometry and the results are compared with experimentally measured in situ thermal history and distortion data, where a reasonable agreement is achieved. The proposed modelling framework with physics-based material constitutive model provides useful information for a better understanding of process–microstructure–property relations in additive manufacturing by DED.

Influence of Processing Route on the Fracture Resistance of Equal Channel Angular Pressing Deformed Iron

The mechanical behavior of pure iron (Armco‐iron) deformed at 200 °C by equal angular channel pressing using processing route BC is investigated with a focus on the fracture properties. In particular, the fracture toughness in terms of elastic–plastic fracture mechanics is evaluated for different specimen orientations with respect to the last deformation step. In addition, the results are comprehensively compared with material processed by route A. The microstructural features of both deformation routes are presented and the underlying microstructure–property relationships are discussed. Both deformation routes (A and BC) lead to a comparable strength even though the microstructural features differ. Route A contains a banded and well‐aligned structure almost parallel to the extrusion direction. For route BC, the microstructural alignment is rotated with respect to the pre‐crack orientation and the grain structure is more heterogeneous. For both deformation routes, the crack plane orientation plays a significant role in the fracture characteristics. The fracture toughness along the extrusion direction, with substantially low fracture toughness for route A, is markedly enhanced for route BC. Consequently, route BC offers a pathway to obtaining severe plastic deformation (SPD) materials with high damage tolerance and a considerably lower extent of anisotropy.

Dissimilar laser lap welding of Mg and Al alloys using a CoCrFeNi medium-entropy alloy interlayer

Laser welding of Mg to Al dissimilar metals is of great significance in various industries, such as automobile, electrical, electronics, and energy systems, which promotes lightweight composite structure. However, Mg-Al intermetallic compounds (IMCs) have tremendous detrimental effects on the dissimilar metal joining of Mg to Al. In this work, dissimilar Mg/Al alloys joints with CoCrFeNi medium-entropy alloy (MEA) powders interlayer were achieved by the laser welding process, and the effect of different laser powers on the microstructure and mechanical properties of the joints was analyzed, reaching a maximum tensile shear strength of 100.12 MPa. The formation mechanism of the interface was investigated by experimental investigations and thermodynamic calculations. In addition, a numerical simulation of the laser welding process was carried out to reveal the temperature field of the molten pool and the flow change process. Based on the law of multi-component HEA phase formation, the interfacial metallurgical products were calculated and analyzed. The results of the energy dispersive spectroscopy show that the molten CoCrFeNi MEA powders reacted with Al to form Al-rich AlxCoCrFeNi phase, due to a more negative generation enthalpy compared to Mg-Al IMCs. With the increase of laser power, the Al-rich AlxCoCrFeNi phase mixed layer went through four states of agglomeration, continuity, interruption and dispersion, while the IMCs at the interface gradually increased and finally tend to be continuity. Due to the physical barrier of MEA and formation of Al-rich AlxCoCrFeNi phase, the formation of the Mg-Al IMCs phase was effectively suppressed, which improved the shear properties of the joints. The material- microstructure-property relations was established in this work, which facilitated the development of laser welding technology for Mg and Al alloys.

Micromechanical Modeling of AlSi10Mg Processed by Laser-Based Additive Manufacturing: From as-Built to Heat-Treated Microstructures.

The unique microstructure of the alloy AlSi10Mg produced by the laser-based powder bed fusion of metals (PBF-LB/M) provides high-strength and high-strain-hardening capabilities of the material. The microstructure and mechanical properties of 3D-printed, i.e., additively manufactured, AlSi10Mg are significantly altered by post-building heat-treatment processes applied in order to tailor the final properties of the parts. Using an accurate computational model to predict and improve the mechanical performance of 3D-printed samples considering their microstructural features can accelerate their employment in envisaged applications. The present study aims to investigate the correlation between microstructural features and the mechanical behavior of as-built, direct-aged, and T6 heat-treated samples of PBF-LB/M AlSi10Mg under tensile loading using experiment and microstructure-sensitive modeling approaches. Nanoindentation tests are used to calibrate the parameters of the constitutive models for the Al and Si-rich phases. The experimental investigations revealed that heat treatment significantly changes the sub-grain morphology of the Si-rich phase, and this can have a considerable effect on the mechanical behavior of the components. The effect of the modeling of the Si-rich phase in the representative volume elements on the prediction of mechanical behavior is investigated using the J2 plasticity model. The combination of the crystal plasticity model for Al and the J2 plasticity model for the Si-rich phase is used to predict the tensile properties of the as-built and heat-treated states. The predicted results are in good agreement with the experimental results. This approach can be used to understand the microstructure–property relationship of PBF-LB/M AlSi10Mg and eventually tailor heat treatment for PBF-LB/M AlSi10Mg based on the requirement of the application.

Genetic relationship of microstructure and mechanical properties between ferrite/pearlite steel plate and billet

This paper proposed the double-pass compression thermal/force simulation experiment to in situ analyze the phase transformation of continuous casting billet during the controlled rolling and controlled cooling process. The genetic relationship between the central segregation of the billet and solute element distribution of the steel plate, and also the genetic relationship of microstructure and mechanical properties between them were experimentally studied. The results show that the microstructure and mechanical properties between the billet and corresponding batch of steel plate have the genetic relationship, and the link of the relationship is central segregation. The phase transformation of supercooling austenite will be affected by the central segregation of Mn and C elements, and the granular bainite abnormal segregation band is the transformation product of Mn and C element segregation region.

High-Throughput Computing Assisted by Knowledge Graph to Study the Correlation between Microstructure and Mechanical Properties of 6XXX Aluminum Alloy.

It is of great academic and engineering application to study the evolution of microstructure and properties of age-strengthened aluminum alloys during heat treatment and to establish quantitative prediction models that can be applied to industrial production. The main factors affecting the peak aging state strength of age-strengthened aluminum alloys are the precipitates, solid solution elements, grain size effects, and textures formed during the material processing. In this work, these multi-scale factors are integrated into the framework of the knowledge graph to assist the following crystal plasticity finite elements simulations. The constructed knowledge graph is divided into two parts: static data and dynamic data. Static data contains the basic properties of the material and the most basic property parameters. Dynamic data is designed to improve awareness of static data. High-throughput computing is performed to further obtain clear microstructure-property relationships by varying the parameters of materials properties and the characteristics of the structure models. The constructed knowledge graph can be used to guide material design for 6XXX Al-Mg-Si based alloys. The past experimental values are used to calibrate the phenomenological parameters and test the reliability of the analysis process.

Review on the correlation between microstructure and mechanical performance for laser powder bed fusion AlSi10Mg

As important structural materials widely used in aerospace and automotive industries, aluminum alloys are perfect candidates for development of laser metal additive manufacturing (AM). Amongst AM aluminum alloys, laser powder bed fusion (LPBF) AlSi10Mg has received substantial attention due to its good printability and relatively low cost. Great efforts have been devoted to seek optimum process parameters that can enhance mechanical performance. However, a large scattering of material properties arises from the literature data, especially for the as built state, thus casting a shadow over further development of LPBF Al alloys. This review article aims to summarize the recent progresses on the characterization of microstructure, assessment of strengthening and damage mechanisms, evaluation of fracture and fatigue resistance, and attempts to build a primary comprehensive link between mechanical performance and microstructure for the as built state. Following the analysis of the state of the art, the review will finally provide an outlook on additional efforts needed to quantify the microstructure-property relation, based on which maximizing the potential of mechanical performance through optimizing microstructure may be achieved.

Cross-Sectional Preparation of Challenging Devices and Their Scale-Bridging Micro- and Nanoanalytical Characterization

Complex devices like batteries, fuel cells or organic sensors and solar cells are commonly assembled from multiple functional components with different materials properties. To gain a fundamental understanding of the microstructure-property relations of such complex macroscopic structures, their degradation and failure mechanisms by complementary scale-bridging microscopic and spectroscopic techniques, it is desirable to prepare cross sections of entire devices or parts. Most challenging is the generation of electron transparent cross-sectional samples for investigation by (cryo) transmission electron microscopy (TEM); preparing TEM samples of devices consisting of different material classes may be utmost difficult. Therefore, TEM sample preparation is often preceded by the disassembly of a device down to individual components rendering an investigation of relations between the individual components impossible.(Cryo-)ultramicrotomy as well as plasma-FIB as advanced cross-sectioning techniques for challenging samples may solve those issues. Both are capable to generate ultra-thin, electron transparent cross sections of hundreds of micrometers in size being larger than the typical thickness of modern devices.In this contribution, we demonstrate the capabilities of modern (cryo-)ultramicrotomy in conjunction with advanced TEM to characterize such sensitive or reactive and thus challenging devices down to the atomic scale. Examples include battery parts, PEM fuel cells and novel flexible all-organic electronics. The achieved thickness of those cross sections is commonly of the order of a few 10 nm, which even allows for atomic-resolution imaging and advanced spectroscopy for microstructure and defect analyses as well as compositional and chemical-bond investigation, respectively. Hepp et al., Trained Laser-Patterned Carbon as High-Performance Mechanical Sensors, NPJ Flex. Electron. 6 (2022), 3, DOI: 10.1038/s41528-022-00136-0 Beaupain et al., Reaction of Li1.3Al0.3Ti1.7(PO4)3 and LiNi0.6Co0.2Mn0.2O2 in Co-sintered Composite Cathodes for Solid-State Batteries, ACS Appl. Mater. Inter. 13 (2021) 47488-47498, DOI: 10.1021/acsami.1c11750 Li et al., Atomic structure of sensitive battery materials and interfaces revealed by cryo-electron microscopy, Science 358 (2017), 506–510, DOI: 10.1126/science.aam6014 Figure 1

Industrially fabricated in-situ Al-AlN metal matrix composites (part B): The mechanical, creep, and thermal properties

The present study (part B) is a direct continuation of the leading study (part A), in which we had introduced extruded aluminum (Al) + 8.8 and 14.7 vol% aluminum nitride (AlN) metal matrix composites (MMC) manufactured at a cost-effective industrial scale and targeted for structural load-bearing applications with an expected service at elevated temperatures. In the leading study the processing, microstructure of nitrided and extruded Al-AlN MMC and the thermal stability of the extruded Al-AlN MMC as reflected in changes to their tensile mechanical properties induced by annealing up to 600 °C were elaborated. In the present ensuing study we discussed in details the mechanical, thermal and creep properties, active strengthening mechanisms, and microstructure-property relations of Al-AlN MMC annealed at 500 °C for 24 h, which were examined in a broad temperature range of 22–500 °C. In addition to increased Young`s modulus Al-AlN MMC showed high tensile strengths determined at 300 °C, which were superior to any conventional Al alloy, accompanied with reasonably high ductility. At the same time Al-AlN MMC preserved excellent creep performance, which was superior to the heat resistant reference alloys, reduced coefficient of thermal expansion and reasonable thermal conductivity. The results confirmed that reported thermally stable Al-AlN MMC may be considered a promising material with an appealing set of the properties directed for load-bearing structural applications with an expected service at elevated temperatures.

Modeling Sound Absorption of Graded Foam Absorbers via Polynomial Surrogate Technique

Transports and sound absorption performance of foam-based absorbers are influenced by the morphologies of their pore connections. Understanding the microstructure–property relationships of sound absorbers can provide valuable insights and guidance for designing and manufacturing steps. We develop in this paper surrogate models based on the polynomial chaos expansion to predict the acoustic behavior of graded foam absorbers. Regarding the local morphology of foams, three representative factors including the porosity, the cell size, and the membrane closure ratio are considered through a periodic unit cell. Then, the reference maps of transport properties are computed via the hybrid numerical method based on the homogenization technique, surrogates are consequently generated in the designing space involving the morphology features. Finally, after evaluating their convergence characteristics and verification study, the surrogate models are adopted to study foam layers within different graded characteristics. Within a tolerance error, the surrogate models of transport properties offer advantages in terms of the computational efficiency and predictability. Both surrogate model-based investigation and optimization frameworks allow estimating the local morphology factors where the desired sound absorption properties of the graded foam absorbers can be achieved.

Nanoscale defect evaluation framework combining real-time transmission electron microscopy and integrated machine learning-particle filter estimation

Observation of dynamic processes by transmission electron microscopy (TEM) is an attractive technique to experimentally analyze materials’ nanoscale phenomena and understand the microstructure-properties relationships in nanoscale. Even if spatial and temporal resolutions of real-time TEM increase significantly, it is still difficult to say that the researchers quantitatively evaluate the dynamic behavior of defects. Images in TEM video are a two-dimensional projection of three-dimensional space phenomena, thus missing information must be existed that makes image’s uniquely accurate interpretation challenging. Therefore, even though they are still a clustering high-dimensional data and can be compressed to two-dimensional, conventional statistical methods for analyzing images may not be powerful enough to track nanoscale behavior by removing various artifacts associated with experiment; and automated and unbiased processing tools for such big-data are becoming mission-critical to discover knowledge about unforeseen behavior. We have developed a method to quantitative image analysis framework to resolve these problems, in which machine learning and particle filter estimation are uniquely combined. The quantitative and automated measurement of the dislocation velocity in an Fe-31Mn-3Al-3Si autunitic steel subjected to the tensile deformation was performed to validate the framework, and an intermittent motion of the dislocations was quantitatively analyzed. The framework is successfully classifying, identifying and tracking nanoscale objects; these are not able to be accurately implemented by the conventional mean-path based analysis.

Study of the microstructure and mechanical property relationships of gas metal arc welded dissimilar Hardox 450 and S355J2C+N steel joints

This research reports the investigation of the dissimilar welding of Hardox 450 and S355J2C+N steels, which have two different superior properties, by the gas metal arc welding (GMAW) method in terms of microstructure and mechanical properties. Experiments were performed using mechanical tests such as Vickers microhardness (HV 0.1), bending, Charpy V-Notch impact, wear, and tensile test. Optical microscopy (OM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyzes have been implemented. A variation in the welded joint microstructure was observed, which affect the mechanical properties. Grain size distribution in area fraction was determined from the EBSD maps of S355J2C+N steel, welded zone, heat affected zone (HAZ) and Hardox 450 steel. The hardness value was measured 311 ± 8 HV for Hardox 450 base material. While the hardness of the S355J2C+N base metal was ∼187 ± 8 HV, the hardness of the weld center was measured as 249 ± 8 HV. Mechanical strength analysis revealed that the yield strengths of base metals were 513 ± 8 MPa and 1464 ± 8 MPa for S355J2C+N and Hardox 450, respectively. The highest tensile strength of the sample extracted from the longitudinal direction of the welded joint is 899 ± 8 MPa. The highest tensile strength of the transverse sample, which was subjected to the tensile tests, was determined as 699 ± 7 MPa and it fractured from the S355J2C+N steel which has less strength. The joint efficiency was determined as ∼133%. The weld zone has sufficient toughness and the change in toughness values in the HAZ is small. The grain size increased from martensitic Hardox 450 steel region to S355J2C+N region, in addition to this, the hardness decreased with the effect of transition from martensitic structure region to ferritic structure region. The welding zone is compatible with two different materials and has a high plastic deformation capability. With the welding procedure followed in the study, Hardox 450 and S355J2C+N dissimilar materials were successfully combined, and it was determined that this welded joint was scientifically and industrially applicable.

Microstructure-property relationships in HPDC Aural-2 alloy: Experimental and CP modeling approaches

Al–Si alloys fabricated by high-pressure die casting (HPDC) have a broad range of applications. Tailored microstructures of HPDC Al–Si alloy were continuously put forward to fulfill the increasing demand for mechanical performance of components. This paper attempts to build microstructure-property relationships of high-pressure die-casting Al–Si alloy to fulfill the increasing demand for mechanical performance of components by tailoring initial microstructure. Moreover, develop a scale-bridging approach to quantitatively upscale the damage initiation of Al–Si alloy under various stress states from micro to macro scale. Both finite element (FE) simulations and Fast Fourier transform (FFT) simulations were applied to calibrate the crystal plasticity parameters. Stress-strain curves simulated by representative volume elements subjected to periodic boundary conditions were validated with the experimental results from uniaxial tensile tests. The response surface design method was herein adopted to rationally and systematically reveal the impact of microstructural heterogeneity on mechanical properties. Finally, damage initiation curves of porous RVEs with distinct characteristics are acquired in terms of the definition of microstructural inhomogeneity criterion. In conclusion, simulation results suggested that strength-related properties are more relevant to the silicon phase characteristics, whereas strain localizations within RVE are observed in the vicinity of pore phase. Furthermore, the predicted failure displacement indicates a good agreement with the experimental results of macro tensile tests. The damage initiation strain shows significant dependence on the stress states and pore phase features (size, volume fraction and morphology).

Field‐Assisted Sintering of Nb–Al2O3 Composite Materials and Investigation of Electrical Conductivity

Field‐assisted sintering technique (FAST) is used for the preparation of Nb–Al2O3 composite materials. The electrical conductivity is investigated depending on the particle size of the used starting powders and under varying volume contents of the refractory metal in the starting powder mixture. The percolation threshold is investigated and found to be influenced not only by the metal fraction but also by the particle size of the alumina used for sample preparation. For the fine‐ and coarse‐grained alumina, a percolation threshold of 17.5 and 10 vol% Nb is estimated, respectively. Furthermore, the microstructure is investigated to gain a basic understanding of the dependency between microstructural features and the resulting material properties on the macroscopic scale. Also, the influence of the sintering process and the resulting microstructure–properties relationship is considered. It could be shown that the electrical properties are anisotropic because of anisotropy effects caused by the FAST process.

Microstructure, mechanical properties and elemental composition of the terrestrial isopod Armadillidium vulgare cuticle

The exoskeletons of crustaceans are essential for providing protection from predators and other environmental threats. Understanding the structure and mechanical behavior of their natural armor could inspire the design of lightweight and high toughness synthetic materials. Most published work has focused on marine crustacea rather than their terrestrial counterparts, which are exposed to a multitude of unique threats. The interest in the terrestrial isopod Armadillidium vulgare (A. vulgare) has grown but the interrelationship between the microstructure, chemical composition, and mechanical properties has not been thoroughly investigated. Thus, this study aims to elucidate missing details concerning this biological mineralized composite. Exoskeleton specimens were fixated to preserve the intrinsic protein structure. We utilize scanning electron microscopy for microstructure analysis, Raman spectroscopy for elemental analysis, and nanoindentation property mapping to achieve mechanical characterization. The naturally fractured A. vulgare exoskeleton cross-section reveals four subregions with the repeating helicoidal ‘Bouligand’ arrangement most prominent in the endocuticle. The hardness and reduced modulus distributions exhibit a through-thickness exponential gradient with decreasing magnitudes from the outermost to the innermost layers of the exoskeleton. The Raman spectra show a graded spatial distribution of key constituents such as calcium carbonate across the thickness, some of which are consistent with the mechanical property gradient. Potential microstructure, elemental composition, and mechanical property relationships are discussed to explain how the hierarchical structure of this nanolaminate armor protects this species.

Damage Mechanisms and Anisotropy of an AA7010-T7452 Open-Die Forged Alloy: Fatigue Crack Propagation.

The process–microstructure–property relationship of high-strength 7000 series aluminum alloys during fatigue crack propagation (FCP) is highly relevant for safety during the design and service of aircraft structural components. It is scientifically evident that many metallurgical factors affect FCP properties, but partly contradictory or inconclusive results show that the quantitative description of the relationships is still a major challenge among researchers and engineers. Most research focuses on sheet or plate products and investigations lack quantitative information on the process–property relationship between open-die forged thick products and FCP. The present study contributes to this field by investigating the fatigue crack growth behavior of an open-die forged AA7010-T7452 aluminum alloy. Four different forging conditions comprising different characteristic microstructures are comparatively analyzed. The influence of grain size, grain shape, specimen orientation, crystallographic texture, and primary phase particles is investigated. Fractographic analysis reveals different active damage mechanisms during fatigue crack growth. Based on that, the microstructure features relevant to fatigue damage areidentified in each regime of crack growth.

Microstructure-property relationships in cement mortar with surface treatment of microbial induced carbonate precipitation

Microbial induced calcite precipitation (MICP) can protect the surface of porous cement-based materials and enhance the durability of concrete, the efficiency of which depends on the near surface property. Therefore, this paper is aimed to investigate the effects of bacterial solution to cementation solution ratio (1:2, 1:1 and 2:1) and different calcium sources (calcium chloride, calcium nitrate and calcium acetate) on compressive strength and capillary water absorption coefficient of MICP-treated mortar, and attempted to establish the relationship between microstructure and macroscopic property. The results indicated that the surface treatment by MICP significantly reduced the capillary water absorption coefficient, while it slightly affected the compressive strength of mortar. Supplying calcium source of calcium chloride or calcium nitrate, setting bacterial solution to cementation solution volume ratio of 1:1 were beneficial to improve the compressive strength and reduce the coefficient, in which the CH content of the near surface layer was reduced and the calcite content of that was increased, it showed limited influence on the hydration products of the interior substances. Nanoscale calcite generated in the near surface layer consumed the CH and filled in gel pores to increase the Ca/Si ratio of C–S–H. The increased compressive strength was due to the refined pore structure of the near surface layer, in which the combination effect of improved pore structure of the near surface layer and the precipitation layer of MICP on the surface effectively reduced the coefficients.

The Relationship of Phase Structure, Microstructure and Electrical Properties of BNT-BT-BST Ceramic

(0.935-x)Bi0.5Na0.5TiO3-0.065BaTiO3-xBa(Sn0.1Ti0.9O3) ceramics with x(BST) = 0, 0.01, 0.03, 0.05, 0.07, 0.10, and 0.15 wt.% were prepared by a solid-state reaction method. The phase structure, microstructure, dielectric, ferroelectric and energy storage properties analysis of BNT-BT-x(BST) ceramics were also studied. The phase structures of BNT-BT-x(BST) ceramics with difference of x(BST) contents were characterized by X-ray diffraction method (XRD). It was found that the samples showed coexistent phases between rhombohedral and tetragonal morphotropic phase boundary (MPB). The grain growth is inhibited with increase of x(BST) contents, which showed the average gain size decreased from 0.94 to 0.63 µm. The phase transition with the first anomaly temperature at the lower temperature (T FA) gradually decreased from 160 to 74 °C, and then tend to increase from 74 to 151 °C. Meanwhile, the second broad dielectric constant peak at higher temperature (T SA) tended to increase first, and then decrease from 307 to 281 °C. Both T FA and T SA exhibit an obvious dependence on the frequency, which showed the relaxor ferroelectric behavior. The highest density (ρ = 5.79 ± 0.15 g/cm3), recoverable energy storage density (W rec= 0.28 J/cm3) and energy storage efficiency (η = 53.85%) and the piezoelectric coefficient (d 33*= 450 pm/V.) was found in the composition of x(BST) = 0.05 wt.%.