Effect of reinforcement particle size on the corrosion and mechanical properties of spark plasma sintered aluminium matrix composites.

In this study, the effects of different sizes of reinforcing particles on the corrosion behaviour and mechanical properties of aluminium (Al)-based composites produced by spark plasma sintering (SPS) are analysed. In the study, the effects of SPS parameters, including electrical power, applied pressure and sintering temperature, on the consolidation process and microstructure evolution of the composite are closely investigated. The results reveal a nuanced relationship between the sintering conditions and the properties of the particles, which in turn determine the sintering dynamics and the formation of the microstructural features. The evaluation of mechanical properties indicates a remarkable influence of particle size distribution on the hardness of the composites, showing an initial improvement with the introduction of nanoparticles, followed by a slight decrease as the balance between nano- and micron-sized Al2O3 particles shifts. A scanning electron microscopy (SEM) study demonstrates the influence of particle dimensions on the change of grain boundaries and the spatial arrangement of the composite matrix. Electrochemical experiments in a 0.1 M NaCl solution show a consistent corrosion potential (Ecorr) across all samples, while the current densities associated with corrosion (icorr) show considerable variation. The presence of nano-sized Al2O3 particles was found to increase corrosion resistance, in contrast to the detrimental effects observed with larger microparticles. In particular, composites with a bimodal distribution of particle sizes showed a 3.5-fold increase in corrosion resistance compared to pure Al. The specific Al-2n8mAl2O3 composite that exhibited active electrochemical properties at elevated potentials without a defined passivation range emphasises the significant role of particle size. This study draws attention to bimodal microstructures as a promising route to achieving uniformity and improved corrosion resistance in Al matrix composites, while pointing to the need for further research to fully elucidate the operative mechanisms.

Cyclotron production of manganese-52: a promising avenue for multimodal PET/MRI imaging.

BACKGROUND: The integration of positron emission tomography (PET) and magnetic resonance imaging (MRI) holds promise for advancing diagnostic imaging capabilities. The METRICS project aims to develop cyclotron-driven production of 52Mn for PET/MRI imaging. RESULTS: Using the 52Cr(p,n)52Mn reaction, we designed chromium metal targets via Spark Plasma Sintering and developed a separation procedure for isolating 52Mn. Labeling tests were conducted with traditional chelators (i.e. S-2-(4-Isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid) and the 1.4-dioxa-8-azaspiro[4.5]decane-8- carbodithioate ligand to produce radioactive complexes suitable for PET/MRI applications. Our methodology yielded high-quality 52Mn suitable for PET radiopharmaceuticals and PET/MRI imaging. Preliminary studies on phantom imaging using microPET and clinical MRI demonstrated the efficacy of our approach. CONCLUSIONS: The developed technology offers a promising avenue for producing 52Mn and enhancing PET/MRI imaging capabilities. Further in vivo investigations are warranted to evaluate the potential advantages of this hybrid imaging technique.

Enhanced humidity sensing performance of LiF-doped MgTiO3 ceramics via spark plasma sintering.

The fabrication of low-porosity ceramics for humidity sensing is crucial to prevent moisture entrapment, which poses significant challenges. Using Spark Plasma Sintering (SPS), we successfully densified fine-grained ceramic materials based on LiF-doped MgTiO3, comparing them with conventionally sintered counterparts. Structural and microstructural analyses, employing X-ray diffraction and Scanning Electron Microscopy (SEM), were conducted. Investigation into electrical and dielectric properties' variations concerning humidity levels was conducted and revealed that SPS sintered ceramics exhibit heightened sensitivity to moisture, as evidenced by resistivity, capacitance, and response time measurements. The implications of these results are discussed in depth, highlighting the potential of SPS as a promising method for fabricating humidity sensors with improved performance and reduced porosity-related issues.

Spark Plasma Sintering of Pure Titanium: Microstructure and Mechanical Characteristics.

The versatility of titanium (Ti) allows it to be employed in various industries, from aerospace engineering to medical technology, highlighting its significance in modern manufacturing and engineering processes. Spark plasma sintering (SPS) is currently being explored to enhance its properties further and broaden its application range. The current study focuses on exploring and optimizing the effect of SPS temperature (800, 900, 1000, 1100, 1200, and 1400 °C) on pure Ti sintered at 60 MPa in a controlled argon environment with a dwell time of 5 min. All the prepared samples were highly dense with a relative density above 99%, but exhibited significant variations in grain size (10 to 57 µm), tensile yield strength (488 to 700 MPa), ultimate tensile strength (597 to 792 MPa), and ductility (4 to 7%). A microstructural investigation was performed using XRD, SEM, and EDS to predict the influence of sintering temperature on the formation of different phases. The XRD patterns of all sintered samples showed the presence of single-phase α-Ti with hexagonally close-packed Ti. This work is a step forward in optimizing SPS-processed Ti's physical and mechanical properties for enhanced structural and biomedical applications.

Fabrication and Characterization of Biomedical Ti-Mg Composites via Spark Plasma Sintering.

The fabrication of Ti-Mg composite biomaterials was investigated using spark plasma sintering (SPS) with varying Mg contents and sintering pressures. The effects of powder mixing, Mg addition, and sintering pressure on the microstructure and mechanical properties of the composite materials were systematically analyzed. Uniform dispersion of Mg within the Ti matrix was achieved, confirming the efficacy of ethanol-assisted ball milling for consistent mixing. The Young's modulus of the composite materials exhibited a linear decrease with increasing Mg content, with Ti-30vol%Mg and Ti-50vol%Mg demonstrating reduced modulus values compared to pure Ti. Based on density measurements, compression tests, and Young's modulus results, it was determined that the sinterability of Ti-30vol%Mg saturates at a sintering pressure of approximately 50 MPa. Moreover, our immersion tests in physiological saline underscore the profound significance of our findings. Ti-30vol%Mg maintained compressive strength above that of cortical bone for 6-to-10 days, with mechanical integrity improving under higher sintering pressures. These findings mark a significant leap towards the development of Ti-Mg composite biomaterials with tailored mechanical properties, thereby enhancing biocompatibility and osseointegration for a wide range of biomedical applications.

Thermoelectric Performance Enhancement in SnS Polycrystals Owing to Hole Doping Combined with Textured Microstructures.

Recently, the earth-abundant tin sulfide (SnS) has emerged as a promising thermoelectric material due to its phonon and electron structure similar to that of tin selenide (SnSe). However, compared with SnSe, limited progress has been achieved in the thermoelectric property enhancement of SnS. Textured SnS polycrystals with an enhanced thermoelectric performance have been developed in this work. The high carrier mobility benefited from the enhanced texture through the repressing strategy of spark plasma sintering, improving the electrical conductivity. In addition, Sn atom deficiencies in the texture sample led to an increased hole concentration, further boosting the electrical conductivity and power factor. The power factor exceeded 4.10 µW/cm·K2 at 423 K and 5.50 µW/cm·K2 at 850 K. The phonon scattering was strengthened by adjusting the multiscale microstructures including dislocations, defect clusters, etc., leading to an ultralow lattice thermal conductivity of 0.23 W/m·K at 850 K. A figure of merit zT > 1.3 at 850 K and an average zTave of 0.58 in the temperature range 373-850 K were achieved in the SnS polycrystal.

Microstructure and coupling mechanisms in MnBi-FeSiB nanocomposites obtained by spark plasma sintering.

Fabrication and extensive characterization of hard-soft nanocomposites composed of hard magnetic low-temperature phase LTP-MnBi and amorphous Fe70Si10B20 soft magnetic phase for bulk magnets are reported. Samples with compositions Mn55Bi45 + x⋅(Fe70Si10B20) (x = 0, 3, 5, 10, 20 wt.%) were prepared by spark plasma sintering of powder mixtures. Characterization has been performed by X-ray diffraction, scanning and transmission electron microscopy, magnetometry and 57Fe MÓ§ssbauer spectroscopy. It was shown that samples contain crystallized and nanometric LTP-MnBi phases with various elemental compositions depending on the degree of Bi clustering. Complex correlations between starting compositions, processes during fabrication, and functional magnetic characteristics were observed. Unexpected special situations of the relation between microstructure and magnetic coupling mechanisms are discovered. Exchange spring effects of different strengths occur, being very sensitive to morpho-structural and compositional features, which in turn are controlled by processing conditions. An in-depth analysis of related microscopic characteristics is provided. Results of this work suggest that fabrication by powder metallurgy routes, such as spark plasma sintering of hard and soft magnetic powder mixtures, of MnBi-based composites with exchange spring phenomena have a high potential in designing and optimization of suitable materials with tunable magnetic properties towards rare-earth-free permanent magnet applications.

Enhanced microstructure and mechanical properties of ZrN-reinforced AlSi10Mg aluminum matrix composite.

Aluminum matrix composites (AMCs), incorporating Zirconium Nitride (ZrN) as reinforcing additives, demonstrate immense promise for applications in aerospace, automotive, and power generation due to their unique combination of low density, superior mechanical properties, and excellent thermal/electrical conductivity. This study explores the influence of ZrN reinforcement on the microstructure and mechanical properties of AlSi10Mg metal-matrix composites. Utilizing high-energy ball milling (HEBM) and spark-plasma sintering (SPS), ZrN/AlSi10Mg composites were synthesized, achieving nearly full density with uniform ZrN distribution, while phase and chemical transformations were not observed in the bulk composites. The addition of ZrN resulted in a notable increase in hardness of 237% (182 ± 8 HV2), elastic modulus of 56% (114 ± 3 GPa), compressive and tensile strength of 183% (565 ± 15 GPa), and 125% (387 ± 9 GPa), respectively, for composites containing 30% ZrN, compared to the non-reinforced alloy. Experimentally determined coefficients of thermal expansion (CTEs) for composites with 10%, 20%, and 30% ZrN content were 19.8 × 10-6 °C-1, 19.1 × 10-6 °C-1, and 18 × 10-6 °C-1, respectively, which well relates to Schapery's model. These findings contribute to understanding the synthesis, mechanical behavior, and thermal properties of ZrN/AlSi10Mg composites, demonstrating their potential for diverse engineering applications.

Utilizing response surface methodology for the microstructural examination of CeO2/GNP composite coating applied via air plasma spraying and post-treated with spark plasma sintering.

CeO2/GNP coatings were fabricated using a three-step process: high-energy ball milling, spray-drying, and air plasma spray (APS) deposition. Spark plasma sintering (SPS) was employed for post-treatment to densify the coatings. Response surface methodology (RSM) was employed to optimize SPS processing parameters, including temperature, pressure, and holding time, for minimizing porosity. A quadratic model was developed and validated using analysis of variance (ANOVA) to determine the influence of the independent variables. A regression equation was derived to predict porosity based on the process parameters. Scanning elctron microscopy(SEM) measurements revealed a significant 16 % porosity reduction in the densified coating. Interlamellar cracks and microcracks were significantly reduced, improving coating integrity and interface bonding. Enhancement of SPS parameters indicated that higher temperature and pressure combined with shorter holding times yielded minimal porosity. The study demonstrated that higher pressures exhibited a stronger impact on porosity at higher temperatures, while the effect of temperature was more pronounced at a holding time of 4 min. The interaction between pressure and holding time highlighted the importance of considering both parameters for effective porosity control in SPS. The constraints for each parameter have been defined through the optimization process. The set temperature is 950 °C, the pressure is established at 30 MPA, and the duration of the holding time is 4 min.

High-Entropy Diborides-Silicon Carbide Composites by Reactive and Non-Reactive Spark Plasma Sintering: A Comparative Study.

The reactive spark plasma sintering (R-SPS) method was compared in this work with the two-step SHS-SPS route, based on the combination of the self-propagating high-temperature synthesis (SHS) with the SPS process, for the fabrication of dense (Hf0.2Mo0.2Ti0.2Ta0.2Nb0.2)B2-SiC and (Hf0.2Mo0.2Ti0.2Ta0.2Zr0.2)B2-SiC ceramics. A multiphase and inhomogeneous product, containing various borides, was obtained at 2000 °C/20 min by R-SPS from transition metals, B4C, and Si. In contrast, if the same precursors were first reacted by SHS and then processed by SPS under the optimized condition of 1800 °C/20 min, the desired ceramics were successfully attained. The resulting sintered samples possessed relative densities above 97% and displayed uniform microstructures with residual oxide content <2.4 wt.%. The presence of SiC made the sintering temperature milder, i.e., 150 °C below that needed by the corresponding additive-free system. The fracture toughness was also markedly improved, particularly when considering the Nb-containing system processed at 1800 °C/20 min, whereas the fracture toughness progressively decreased (from 7.35 to 5.36 MPa m1/2) as the SPS conditions became more severe. SiC addition was found to inhibit the volatilization of metal oxides like MoO3 formed during oxidation experiments, thus avoiding mass loss in the ceramics. The benefits above also likely took advantage of the fact that the two composite constituents were synthesized in parallel, according to the SHS-SPS approach, rather than being produced separately and combined subsequently, so that strong interfaces between them were formed.

Effect of Metal Elements on Microstructure and Mechanical Properties of Ultrafine Cemented Carbide Prepared by SPS.

To satisfy the needs of precision machining, ultrafine tungsten carbide (WC)-based cemented carbide with fine grain size and excellent mechanical properties was prepared. Ultrafine cemented carbide was prepared by spark plasma sintering (SPS) using WC, Co as raw materials and metal elements V, and Cr as additives, and the effects of metal elements on the microstructure and mechanical properties of cemented carbide were investigated. The results show that the specimen (91.6WC-1.2V-1.2Cr-6Co) prepared at 1350 °C, 6 min, 25 MPa has the best mechanical properties (HV 2322.9, KIC 8.7 MPa·m1/2) and homogeneous microstructure. The metal elements could react with WC to form a (W, V, Cr) Cx segregation layer, which effectively inhibits the growth of WC grains (300 nm). The combination of SPS and metal element additives provides a new approach for the preparation of ultrafine cemented carbides with excellent properties.

Study on the Effect of Sn, In, and Se Co-Doping on the Thermoelectric Properties of GeTe.

GeTe and Ge0.99-xIn0.01SnxTe0.94Se0.06 (x = 0, 0.01, 0.03, and 0.06) samples were prepared by vacuum synthesis combined with spark plasma sintering (SPS). The thermoelectric properties of GeTe were coordinated by multiple doping of Sn, In, and Se. In this work, a maximum zT(zT = S2σT/κ) of 0.9 and a power factor (PF = S2σ) of 3.87 µWmm-1 K-2 were obtained in a sample of Ge0.99In0.01Te0.94Se0.06 at 723K. The XRD results at room temperature show that all samples are rhombohedral phase structures. There is a peak (~27°) of the Ge element in GeTe and the sample (x = 0), but it disappears after Sn doping, indicating that Sn doping can promote the dissolution of Ge. The scattering mechanism of the doped samples was calculated by the conductivity ratio method. The results show that phonon scattering Is dominant in all samples, and alloy scattering is enhanced with the increase in the Sn doping amount. In doping can introduce resonance energy levels and increase the Seebeck coefficient, and Se doping can introduce point defects to suppress phonon transmission and reduce lattice thermal conductivity. Therefore, the thermoelectric properties of samples with x = 0 improved. Although Sn doping will promote the dissolution of Ge precipitation, the phase transition of the samples near 580 K deteriorates the thermoelectric properties. The thermoelectric properties of Sn-doped samples improved only at room temperature to ~580 K compared with pure GeTe. The synergistic effect of multi-element doping is a comprehensive reflection of the interaction between elements rather than the sum of all the effects of single-element doping.

Effect of Nitrogen Atmosphere Annealing of Alloyed Powders on the Microstructure and Properties of ODS Ferritic Steels.

Oxide Dispersion Strengthened (ODS) ferritic steels are promising materials for the nuclear power sector. This paper presents the results of a study on the sintering process using the Spark Plasma Sintering (SPS) technique, focusing on ODS ferritic steel powders with different contents (0.3 and 0.6 vol.%) of Y2O3. The novelty lies in the analysis of the effect of pre-annealing treatment on powders previously prepared by mechanical alloying on the microstructure, mechanical, and thermal properties of the sinters. Using the SPS method, it was possible to obtain well-densified sinters with a relative density above 98%. Pre-annealing the powders resulted in an increase in the relative density of the sinters and a slight increase in their thermal conductivity. The use of low electron energies during SEM analysis allowed for a fairly good visualization of the reinforcing oxides uniformly dispersed in the matrix. Analysis of the Mössbauer spectroscopy results revealed that pre-annealing induces local atomic rearrangements within the solid solution. In addition, there was an additional spectral component, indicating the formation of a Cr-based paramagnetic phase. The ODS material with a higher Y2O3 content showed increased Vickers hardness values, as well as increased Young's modulus and nanohardness, as determined by nanoindentation tests.

Nano-Structure Evolution and Mechanical Properties of AlxCoCrFeNi2.1 (x = 0, 0.3, 0.7, 1.0, 1.3) High-Entropy Alloy Prepared by Mechanical Alloying and Spark Plasma Sintering.

The AlxCoCrFeNi2.1 (x = 0, 0.3, 0.7, 1.0, 1.3) multi-component high-entropy alloy (HEA) was synthesized by mechanical alloying (MA) and Spark Plasma Sintering (SPS), The impact of the percentage of Al on crystal structure transition, microstructure evolution and mechanical properties were studied. Crystal structure was investigated by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The results show that with the increasing of Al content, the crystal structure of the alloys gradually transformed from a nanocrystalline phase of FCC to a mix of FCC and BCC nanocrystalline. The hardness was found to increase steadily from 433 HV to 565 HV due to the increase in fraction of BCC nanocrystalline phase. Thus, the compressive fracture strength increased from 1702 MPa to 2333 MPa; in contrast, the fracture strain decreased from 39.8% to 15.6%.

Enhanced Thermoelectric Properties of P-Type Sn-Substituted Higher Manganese Silicides.

This study introduces Sn-substituted higher manganese silicides (MnSi1.75, HMS) synthesized via an arc-melting process followed by spark plasma sintering (SPS). The influences of Sn concentrations on the thermoelectric performance of Mn(Si1-xSnx)1.75 (x = 0, 0.001, 0.005, 0.01, 0.015) are systematically investigated. Our findings reveal that metallic Sn precipitates within the Mn(Si1-xSnx)1.75 matrix at x ≥ 0.005, with a determined solubility limit of approximately x = 0.001. In addition, substituting Si with Sn effectively reduces the lattice thermal conductivity of HMS by introducing point defect scattering. In contrast to the undoped HMS, the lattice thermal conductivity decreases to a minimum value of 2.0 W/mK at 750 K for the Mn(Si0.999Sn0.001)1.75 sample, marking a substantial 47.4% reduction. Consequently, a figure of merit (ZT) value of ~0.31 is attained at 750 K. This considerable enhancement in ZT is primarily attributed to the suppressed lattice thermal conductivity resulting from Sn substitution.

Study of Electrical and Dielectric Behaviors of Copper-Doped Zinc Oxide Ceramic Prepared by Spark Plasma Sintering for Electronic Device Applications.

In this study, Cu-doped ZnO aerogel nanoparticles with a 4% copper concentration (Cu4ZO) were synthesized using a sol-gel method, followed by supercritical drying and heat treatment. The subsequent fabrication of Cu4ZO ceramics through Spark Plasma Sintering (SPS) was characterized by X-ray diffraction (XRD), field-emission gun scanning electron microscopy (FE-SEM) equipped with EDS, and impedance spectroscopy (IS) across a frequency range of 100 Hz to 1 MHz and temperatures from 270 K to 370 K. The SPS-Cu4ZO sample exhibited a hexagonal wurtzite structure with an average crystallite size of approximately 229 ± 10 nm, showcasing a compact structure with discernible pores. The EDS spectrum indicates the presence of the base elements zinc and oxygen with copper like the dopant element. Remarkably, the material displayed distinct electrical properties, featuring high activation energy values of about 0.269 ± 0.021 eV. Complex impedance spectroscopy revealed the impact of temperature on electrical relaxation phenomena, with the Nyquist plot indicating semicircular arc patterns associated with grain boundaries. As temperature increased, a noticeable reduction in the radius of these arcs occurred, coupled with a shift in their center points toward the axis center, suggesting a non-Debye-type relaxation mechanism. Dielectric analyses revealed a temperature-driven evolution of losses, emphasizing the material's conductivity impact. Non-Debye-type behavior, linked to ion diffusion, sheds light on charge storage dynamics. These insights advance potential applications in electronic devices and energy storage.

Using the Spark Plasma Sintering System for Fabrication of Advanced Semiconductor Materials.

The interest in the Spark Plasma Sintering (SPS) technique has continuously increased over the last few years. This article shows the possibility of the development of an SPS device used for material processing and synthesis in both scientific and industrial applications and aims to present manufacturing methods and the versatility of an SPS device, presenting examples of processing Arc-Melted- (half-Heusler, cobalt triantimonide) and Self-propagating High-temperature Synthesis (SHS)-synthesized semiconductor (bismuth telluride) materials. The SPS system functionality development is presented, the purpose of which was to broaden the knowledge of the nature of SPS processes. This approach enabled the precise design of material sintering processes and also contributed to increasing the repeatability and accuracy of sintering conditions.

Spark plasma sintered porous Ni as a novel substrate of Ni3Se2@Ni self-supporting electrode for ultra-durable hydrogen evolution reaction.

Developing efficient and durable self-supporting catalytic electrodes is an important way for industrial applications of hydrogen evolution reaction. Currently, commercial nickel foam (NF)-based electrode has been widely used due to its good catalytic performance. However, the NF consisting of smooth skeleton surface and large pores not only exhibits poor conductivity but also provides insufficient space for catalyst decoration and sufficient adhesion, resulting in inadequate catalytic performance and poor durability of NF-based electrodes. In this paper, a novel three-dimensional porous Ni substrate with multangular skeleton surface and small pore structure was prepared by a modified spark plasma sintering technique, and subsequently Ni3Se2@Porous Ni electrode with a large number of Ni3Se2 nanosheets uniformly distributed on the surface was obtained by one-step in-situ selenization. The electrode exhibits outstanding conductivity and catalytic hydrogen evolution reaction, providing a low overpotential of 183 mV at a current density of 100 mA cm-2. Due to the strong interfacial bonding between Ni and Ni3Se2, the Ni3Se2@Porous Ni electrode shows strong durability, which can work stably at 85 mA cm-2 for more than 200 h. This work provides an effective strategy for the rational preparation of metal substrates for efficient and durable self-supporting catalytic electrodes.

Phase stability and microstructural properties of high entropy alloy reinforced aluminium matrix composites consolidated via spark plasma sintering.

Spark plasma sintering (SPS) technique was employed in the consolidation of Cr20Mn20Ni20Cu20Nb10Co10 high entropy alloy (HEA) reinforced aluminium matrix composites. Phase stability and prediction expressions were used in the determination of the powder combination for the HEA. The microstructural analysis showed that an interdiffusion layer was formed between the aluminium matrix and the HEA particles in the sintered composites. Further investigation of the composites by X-ray diffraction (XRD) showed that in addition to the Al matrix phase present, other new phases (BCC, FCC and other intermetallics) were formed as a result of the reaction between the Al matrix and the atoms precipitated from the added HEA during sintering. The density of the HEA-reinforced Al matrix composites decreases with an increase in the wt.% of HEA from 98.6 % for pure aluminium to 98.1 % for the reinforced alloy with 10 % HEA, while the microhardness increases with an increase in the wt.% of the HEA from 35 HV for pure aluminium to 96.0 HV for the alloy reinforced with 10 % HEA.

Electrochemical Performance and Microstructure Evolution of a Quasi-Solid-State Lithium Battery Prepared by Spark Plasma Sintering.

Solid-state lithium batteries are promising next-generation energy storage systems for electric vehicles due to their high energy density and high safety and require achieving and maintaining intimate solid-solid interfaces for lithium-ion and electron transport. However, the solid-solid interfaces may evolve over cycling, disrupting the ion and electron diffusion pathways and leading to rapid performance degradation. The development of solid-state lithium batteries has been hindered by the lack of fundamental understanding of the interfacial microstructure change over cycling and its relation to electrochemical properties. Herein, we prepared a quasi-solid-state lithium battery, 30%LiFePO4-55%Li1.5Al0.5Ge1.5(PO4)3-15%C| Li1.5Al0.5Ge1.5(PO4)3|Li, by spark plasma sintering, and employed it as a model system to reveal the microstructure evolution at the solid-solid interfaces with electrochemical performance of the batteries. The electrochemical assessment showed that the quasi-solid-state lithium battery exhibited a discharge specific capacity of about 150 mAh g-1 in the first 80 cycles and then experienced severe capacity attenuation afterward, accompanied by a gradual internal resistance increase. Scanning electron microscopy observation showed that more cracks were formed inside the solid-state electrolyte and at the solid-solid interfaces as the battery cycled from 10 to 67 and 157 cycles. Detailed microstructure and phase analysis by high-resolution transmission electron microscopy and selected area electron diffraction discovered that the crack formation and performance decay were mainly caused by (1) the volume change of the LiFePO4 composite cathode during cycling, (2) the grain expansion of the Li1.5Al0.5Ge1.5(PO4)3 solid-state electrolyte at its interface with lithium anode, and (3) the formation of a solid electrolyte interphase layer, comprising Li2CO3, LiF, and LiTFSI, at the cathode-solid-state electrolyte interface. These microstructure changes built up over repeated battery cycling, ultimately causing the structure collapse and battery failure. The microstructure evolution information is expected to guide the design of better structures and interfaces for solid-state lithium batteries.