Ceramic Grains Research Articles

Microstructure and mechanical properties of (Nb,W,Ti)(C,N)-Ni solid solution cermets with 6 to 20 wt% Ni

Ni bonded (Nb,W,Ti)(C,N) solution cermets with overall compositions of NbC-(6–20)Ni-18WC-14 Ti(C0.7N0.3) (wt%) were prepared by pressureless vacuum sintering of compacted NbC, Ni, WC and Ti(C0.7N0.3) mixtures. The microstructure, phase constitution, room temperature mechanical properties were investigated and the phase composition in the cermets sintered at 1450 °C was simulated by thermodynamic modelling. The sintered cermets exhibited a microstructure of a cubic Ni alloy binder dispersed in the matrix of core-rim structured (Nb,W,Ti)(C,N) complete solid solution grains. The average ceramic grain size was in the range of 1.5–2.1 μm and increased with increasing binder content and sintering temperature. The hardness decreased whereas the fracture toughness and flexural strength increased with increasing Ni content. For the cermets sintered at 1450 °C, the 6 wt% Ni cermet had a hardness of 1627 kg/mm2, a toughness of 7.8 MPa.m1/2 and a flexural strength of 1478 MPa. The toughness and strength were improved to 13.1 MPa.m1/2 and 2446 MPa in the cermet with 20 wt% Ni.

Enhanced mechanical and sintering properties of MgO-TiO2 ceramic composite via digital light processing

In this work, MgO was applied to modify the titania ceramic slurry, which could realize the high-quality DLP printing of titania ceramic by promoting the grain growth during sintering. Combining the phase and element analysis, it was revealed that the reduced stress concentration and improved mechanical property were attributed to the formation of MgTi2O5 in solid-state reaction between MgO and TiO2. When MgO content increased beyond 10 wt.%, the microstructure pinning effects showed a negative impact on ceramic grain growth. Among all the samples, 5%MgO/TiO2 has exhibited the best bending strength of 71.9 MPa and the densification of 85%, while its sintering temperature reduced by 200 °C. Meanwhile, the compressive property of representing porous TiO2 samples reached 18.2 MPa, which was similar to those of porous ceramics produced by conventional manufacturing routes. Overall, MgO-TiO2 composite ceramic prepared in this study have potential application in field of monolithic catalysts and tissue engineering scaffold.

Cu/W Co-doped CaBi2Nb2O9 piezoelectric ceramics on structural and electrical properties

This article reports the significantly improved piezoelectric and ferroelectric properties of Cu/W co-doped Ca2Bi2Nb2-x(Cu1/4W3/4)xO9 (CBNCW-x, where 0 ≤ x ≤ 0.150) high Curie temperature lead-free piezoelectric ceramics. The crystal structure, microstructure, and electric properties of CBNCW-x ceramics have been systematically analyzed. The results show that ceramic samples have a bismuth layered structure of m= 2, which is a single-phase of CBN. The ceramic grains show the typical plate-like structure of the bismuth layer. Cu/W co-doped CBN ceramics increased the distortion of NbO6 octahedron, and significantly enhanced the piezoelectric constant and the remnant polarization. When x = 0.075, it shows better comprehensive properties with an excellent d33 of 13.8 pC/N, a high remnant polarization of 12.10 μC/cm2, the Tc of 918 °C, a dielectric loss value of 0.57%, and the Qm value of 7099. Moreover, CBNCW-0.075 ceramic simple maintains the d33 of 12.7 pC/N after annealing 900 °C for 30 min, which shows good high-temperature stability. It suggests that the Cu/W co-doped CBN ceramics have good application prospects in the high-temperature piezoelectric field.

Crystallization and Dielectric Properties of BaO-SrO-PbO-TiO2-Nb2O5-SiO2 Glass-Ceramic Composites with La2O3 Addition

Glass-ceramic composite samples with different La2O3 content were prepared via melt-quenching followed by controlled crystallization. X-ray diffraction(XRD) analysis reveals that when the addition amount of La2O3 in the glass sample is less than 1mol%, two phases of perovskite structure and tungsten-bronze structure are formed after annealing at 1000°C for 3h. When the addition amount of La2O3 in the glass sample is increased to 2mol%, a new phase of pyrochlore structure is formed. Moreover, the addition of La2O3 causes the change in the lattice parameters of the glass-ceramic crystal phase. The microstructure observed that the ceramic phase grain size is in the nanometer level. The shape of some grains becomes an elongated structure when the La2O3 content in the sample increases to 2 mol%, and the grain size is increased significantly. The dielectric constant of the BaO-SrO-PbO-TiO2-Nb2O5-SiO2 glass-ceramic system is decreased with the increase of La2O3 addition, and the dielectric loss of the sample is decreased to the range of 0.003-0.008. The electric field stability of the dielectric constant was significantly improved with the addition of La2O3, indicating that adding a certain proportion of La2O3 to the BaO-SrO-PbO-TiO2-Nb2O5-SiO2 glass-ceramic system can effectively improve the dielectric properties, and it has a promising application as a dielectric material.

Dielectric and piezoelectric properties of PLZT x/40/60 (x = 5; 12) ceramics

The paper presents the results of studies of the structure, piezoelectric and dielectric properties of lead zirconate-titanate ceramics modified with lanthanum of various concentrations (PLZT). It was found that with an increase in the La content, the grain size and the average domain size increase. The PLZT 12/40/60 samples contain both labyrinth-like and periodic domains, as well as different lateral sizes from several hundred nanometers to 3 microns in diameter. It was found that the piezoelectric response signal increases with increasing domain sizes in samples with a high lanthanum content. The fact of the existence of areas on surface of PLZT x/40/60 ceramics having an internal displacement field is established, as evidenced by the asymmetry of the remnant piezoelectric hysteresis loops along the voltage axis. In the samples PLZT 5/40/60 and PLZT 12/40/60, a significant dispersion of the permittivity ε(f) and a maximum of the tangent of the dielectric loss angle were observed in the frequency range from 105 to 106 Hz. This is due to the presence of ionic relaxation polarization, as is the case in ionic dielectrics. It is established that the value of the dielectric constant increases markedly with increasing La, which confirms the occurrence of a rigid unipolar state in the PLZT 12/40/60 ceramic grains. In the samples under study, an increase in the tangent of the dielectric loss angle is observed at low frequencies of the measuring field, which is associated with the contribution of conductivity to tg δ. The dependences of the dielectric loss factor ε” on the dielectric permittivity ε’are constructed. They have the form of Cole-Cole diagrams, which indicates the presence of a relaxation time spectrum, while it was found that the spectrum width in PLZT 5/40/60 samples is about two times less than in PLZT 12/40/60 samples.

Relaxation processes and conduction behaviour in PVDF-TrFE and KNN-based composites

Polymer-ceramic composites have gained considerable attention in flexible electronic devices due to their uncommon features such as high dielectric constant, low conductivity, and good mechanical flexibility. The electrical and mechanical responses of various components (ceramic grain & grain boundary, polymer chains, and interface) need to be elucidated to rationally design high-performance polymer-ceramic composites. This paper provides a detailed analysis of dynamic mechanical and frequency-dependent dielectric behaviour with temperature to discern the various mechanisms responsible for the relaxations in the polyvinylidene fluoride-trifluoro ethylene/K0·5Na0·5NbO3–CaZn1/3Ta2/3O3 (PVDF-TrFE/KNN-1CZT) composite fabricated using solution casting technique. The FTIR spectra and x-ray diffraction patterns indicate the existence of the polar β-phase, confirming the ferroelectric nature of polymer films. The ferroelectric-paraelectric phase transition (TC ∼ 130 °C) of polymer film obtained from the DSC & DMA data was corroborated by the dielectric study. The introduction of ceramic fillers in polymer induces an additional relaxation in the 10 kHz to 1 MHz frequency range, owing to the ceramic-polymer interface formation, which is responsible for increment in the dielectric constant and storage capacity of the composites. The effective dielectric constant of the composite was modelled using the Maxwell-Garnet and Yamada models. The enhanced dielectric constant of composite films (εr ∼ 28) with the addition of dielectric filler qualifies these materials for flexible high-performance capacitive devices. Further, this study enables a better understanding of the various relaxation processes in the composite with dielectric fillers.

Microstructure and electrical conductivity of 10% Yb-doped SrCeO3 ceramics

As a candidate material for hydrogen separation, Yb-doped SrCeO3 has attracted increasing attention in recent decades. In the present study, Yb-doped SrCe0.9Yb0.1O3-α ceramics were prepared by the dry pressing and sintering approach, with the microstructure evolution and the micro morphology investigated. It was indicated that the ceramics sintered in air were of a pure perovskite structure, and that the sintering temperature had a significant effect on the growth of ceramic grains. The average grain size increased from 1 ​μm to 10 ​μm with an increase in sintering temperature from 1300 to 1500 ​°C. Further investigation of the thermodynamics and kinetics of grain growth revealed that the grain boundary diffusion was the main driving force of grain growth during solid phase sintering, with a grain growth index of 4 and an activation energy of approximately 61.23 ​kJ ​mol−1. These results illustrate an obvious tendency of grain size growth. By electrochemical workstation with different atmospheres the effects of sintering temperature on the conductivity were characterized in the temperature range of 700–900 ​°C. The electrical conductivities σ of SrCe0.9Yb0.1O3-α ceramics in different atmospheres were as follows: σ(wet hydrogen) ​> ​σ(dry hydrogen) ​> ​σ(dry air) ​> ​σ(wet air). In the test atmosphere containing water and hydrogen the conductivity of protons increased with increasing temperature because of the protons jump between lattices in the form of interstitial hydrogen ions or bare protons.

Microstructures and properties of 45S5 bioglass® & BCP bioceramic scaffolds fabricated by digital light processing

The porous bioceramic scaffolds require favorable mechanical properties and excellent bioactivity to promote bone repair. In this work, 45S5 bioglass® & biphasic calcium phosphate (BCP) bioceramic scaffolds with a diamond lattice structure (porosity of 70%) were manufactured accurately by digital light processing (DLP). After optimizing the solid loading of bioceramic suspension to 40 vol%, scaffolds with the minimum pore size of 400 µm were fabricated successfully under exposure energy of 12.54 mJ/cm2. In the initial stage of sintering, crystallization occurred during 45S5 bioglass® itself, bioglass also promoted hydroxyapatite (HA) decomposition to tricalcium phosphate (TCP). With extending holding time to 4 h, Si4+ from 45S5 bioglass® diffused into TCP to produce Ca5(PO4)2SiO4, which could enhance the compressive strength of bioceramic scaffolds. Meanwhile, bioglass would assist the growth and roughening of ceramic grains because of the ion-diffusion from bioglass to BCP. However, as holding time extended to 6 h, abnormal grain growth and cracks occurred which would decrease compressive strength. The best value of compressive strength is 1.735 MPa at the holding time of 4 h. 45S5 bioglass® also accelerated ion exchange such as Si4+ and CO32- between bioceramic and SBF solution. This kind of bioceramics may be used as bioactive scaffolds with customizable fine structures and provide potential applications in bone tissue engineering.

Monolithic ZrB2‐based UHTCs using polymer‐derived Si(Zr,B)CN as sintering aid

AbstractIn the present work, dense ZrB2‐based monoliths were produced via hot‐pressing of ZrB2 powders coated with amorphous polymer‐derived SiCN, SiZrCN, or SiZrBCN at relatively moderate temperatures (i.e., 1800℃). Thus, ZrB2 particles were embedded in polymer‐derived ceramic shell were realized by coating their surface with the corresponding polymeric precursors (polysilazane, Zr‐modified polysilazane, Zr‐ and B‐modified polysilazane, as for SiCN, SiZrCN, and SiZrBCN; respectively), followed by cross‐linking at 200℃ and pyrolysis at 1100℃ in Ar atmosphere. The obtained monolithic samples were carefully characterized concerning their phase composition and microstructure. Typically, the densified samples exhibit a homogeneous microstructure consisting of ZrB2 grains and a multi‐phasic polymer‐derived ceramic grain boundary phase (β‐SiC, t‐BCN, ZrO2, and ZrC). The prepared monoliths exhibited fair hardness values, that is, 12.5, 14.2, and 13.3 GPa for ZrB2/SiCN, ZrB2/SiZrCN, and ZrB2/SiZrBCN.

The solubility, microstructure, and chemical durability of Ce‐doped YIG ceramics designed as actinide waste forms

Yttrium iron garnet (YIG) is a potential matrix for immobilizing high-level radioactive waste (HLW) due to its high actinide solubility and chemical flexibility. In this study, Ce was employed as a surrogate of Pu. A series of Y3-xCexFe5O12 (0 ≤ x ≤ 1) samples were prepared by solid-state sintering at 1400°C to investigate the solubility, microstructure, and chemical durability of Ce-doped YIG. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the solubility of the Ce in a single garnet was 32 mol% at synthesis temperature of 1400°C. The SEM analysis indicated the YIG ceramic grain growth and compactness as Ce concentrations increased. The XPS analysis indicated that the amount of Ce4+ out of the total Ce increased as the CeO2 doping increased, and the maximum value was more than 75.9% in the sample synthesis at 1400°C. Static leaching experiments were also conducted on the single Ce-doped garnet synthesized at 1400°C. The normalized LRCe and LRY release rates were approximately 10−4 and 10−5 g m−2 d−1 after 42 days, respectively. The chemical durability was comparable to other ceramic matrices (such as pyrochlore and zircon, among others). These results demonstrated that YIG ceramics are suitable for immobilizing HLW, such as Pu or U. Highlights The solubility of Ce in single-phase YIG was 32 mol% at 1400°C. Grain size and compactness increased Ce content. The concentration of Ce4+ in total Ce of sample could be over 75.9%. The obtained YIG ceramics exhibit excellent chemical stability. Novelty Statement Y3-xCexFe5O12 ceramics were prepared by solid-state sintering and the solubility, microstructure, and chemical durability were investigated. The solubility of Ce was 32 mol% at 1400°C. The obtained YIG ceramics exhibit excellent chemical stability.

Effects of AlN Content and Sintering Atmospheres on the Thermal Conductivity of Hot-Pressed SiC Ceramics

In pursuit of high thermal conductivity of SiC ceramics, this article reports the effects of AlN and sintering atmospheres on the thermal properties and microstructure evolution of SiC ceramics. Dense SiC ceramics with different contents of AlN additive were fabricated through hot-press sintering at 1950°C in Ar/N2 atmosphere under a pressure of 40 MPa for 3 h. The results showed that the thermal conductivity of samples without AlN addition was 53.5 W.m−1.K−1 when sintered in Ar and 50.3 W.m−1.K−1 when sintered in N2. The SiC ceramics with 4 wt% AlN sintered in Ar showed abnormally large grains and exhibited the highest thermal conductivity of 121.7 W.m−1.K−1 among all the samples. The sample with 2 wt% AlN sintered in N2 exhibited a thermal conductivity of 108.6 W.m−1.K−1; the thermal conductivity deceased with the increasing AlN content afterwards. Such a decreasing trend of thermal conductivity was attributed to the ascending 2Hss content and smaller grains of ceramics. There existed an optimal content of AlN and a proper sintering atmosphere for perfecting the microstructure and the thermal conductivity of SiC ceramics.

Influence of sintering temperature on microstructure of Na0.5Bi0.5TiO3 ceramics

Na0.5Bi0.5TiO3 (NBT)-based compositions are among the most promising lead-free ferroelectrics. Although studies of modification of NBT-based compositions’ properties are a hot topic, there has been very little attention paid to their characterization from the standpoint of ceramics and the process of producing them. Here, we report on comprehensive analysis of the influence of sintering temperature across a wide temperature range (1020–1240 °C) on the complete microstructure and chemical content of NBT ceramics produced by solid state sintering, which is dominating in producing of NBT ceramics. Thorough attention is paid to the grain size distribution, porosity, and inhomogeneity. It is demonstrated how the grain size distribution monotonously becomes more diffuse and the average grain size increases, upon sequential increasing of the sintering temperature. Along with high density (reaching 98% of the theoretical value), two types of pores are observed. Macroscopic pores form at high sintering temperatures along with a small concentration of residual pores remaining after densification of ceramics and observed throughout the whole range of sintering temperatures. Two types of inclusions are detected, corresponding to the chemical compositions NaBiTi6O14 and TiO2, as inferred from local energy-dispersive X-ray analysis. Non-intentional non-stoichiometry is not detected in the matrix grains of the NBT ceramics, even if sintered at high temperatures. It is inferred that, instead of changing the composition of the matrix grains, Na and Bi volatilization rather influences the porosity and inhomogeneity of NBT.

High-temperature digital image correlation techniques for full-field strain and crack length measurement on ceramics at 1200°C: Optimization of speckle pattern and uncertainty assessment

High-temperature mechanical tests coupled with Digital Image Correlation (DIC) on ceramics which exhibit rather low level of strain require to overcome extreme experimental conditions that usually can reduce significantly measurement accuracy. Thermal resistance of speckle pattern, black body radiation and heat haze are three main concerns, which should thus be taken into account while designing a high-temperature image acquisition setup. In this aim, an experimental procedure has been specifically designed in order to minimize the three above-mentioned disturbances. The main objective of this study is to select a suitable high-temperature resistant speckle pattern for mechanical characterization at 1200 °C (or above) on refractory ceramics. Most of tested speckle patterns were performed with white alumina adhesive and dark ceramic grains (silicon carbide or brown fused alumina). Different grain sizes of silicon carbide were tested. At first, different speckle patterns are compared in terms of DIC strain measurement uncertainty by discussing speckle features, some main DIC parameters and two image pre-treatments (low pass filter, image size reduction). Then, these speckle patterns are tested to analyse fracture behaviour of refractories through a Brazilian test. An enhanced digital image correlation technique (2P-DIC), dedicated to monitor the fracture behaviour, is applied to study the evolution of crack length. The best representation of crack progression has been achieved for sample surface covered with a fine SiC powder ranging from 50 to 100 µm. It is then possible to compare the fracture behaviour between 1200 °C and 20 °C and to show that the refractory exhibits more crack branching at 1200 °C in comparison with behaviour at room temperature.

Effect of thermal treatment conditions on the solid-state synthesis of barium zirconate from barium carbonate and monoclinic zirconia

In the present work the solid-state synthesis of phase-pure barium zirconate (BaZrO3) using barium carbonate and monoclinic zirconia as powder raw materials is investigated. Due to the high evaporation tendency of BaO, special attention is paid to the thermogravimetric behaviour of stoichiometric mixtures of BaCO3 and ZrO2, namely without sintering aids. DSC/TG measurements of the powder mixtures were conducted to assess the synthesis reaction using heating rates of 1, 3 and 10 K min−1. In addition to the investigations of the thermogravimetric behaviour in dependence of different heating rates, the influence of synthesis temperature and ceramic carrier grains was examined on pressed specimens of 50 mm in diameter. Moreover, the influence of three different partial pressure relations resulting from the decarbonisation reaction and the assumed BaO evaporation was investigated. It was found that a synthesis temperature of 1200 °C and a heating rate of 1 K min−1 resulted in the least pronounced mass loss and mass loss rate, respectively. XRD analyses revealed phase-purity for specimens of assumed low BaO evaporation. Thus, optimum thermal treatment conditions were identified for the BaZrO3 synthesis that can be applied to the production of phase-pure material for e.g. the refractory industry.

Subsurface multilayer evolution of ZrB2–SiC ceramics in high-speed sliding and adhesion transfer conditions

High-speed continuous sliding experiments on ZrB2-20 vol% SiC ultra-high temperature ceramics have been carried out to elucidate specifics and details of tribooxidation under conditions of subsurface deformation and friction generated heating. Subsurface multilayer structure layer phase composition was obtained to testify on the intense mass transfer processes. Generation of thick boron-depleted and mechanically mixed layer (MML) composed of silicate glass, iron, high-temperature zirconia phases as well as silicon carbide insulated the underlying ZrB2 grains and served to generation of two transition layers composed of borosilicate glass, zirconia and iron oxyborides. This and sealing the voids and cracks by borosilicate glass had its effect on oxidation of silicon carbide grains, which might have caused intense formation of spherical particles even far below the worn surface. Mass transfer of iron and oxygen into ceramic composite grains has been discovered along with evaporation of boron anhydride from the MML.

High-optical-quality non-cubic Yb3+-doped Ca10(PO4)6F2 (Yb:FAP) laser ceramics

We fabricated an advanced transparent Yb-doped hexagonal fluorapatite ceramic with an average grain size of only 90 nm; we also demonstrated its laser oscillation. To the best of our knowledge, this is the smallest grain size for laser ceramics. The in-line transmittance was 86.1% at 1 µm for 0.79-mm-thick ceramics (corresponding to a loss coefficient of 0.45 cm-1). Although the ceramic crystal grains were randomly oriented, scattering at the grain boundary was suppressed because the grains were considerably smaller than the wavelength. This novel ceramic possesses both a fine microstructure and densification and is expected to be the foundation of many non-cubic laser ceramics.

Self-lubricating ceramic tool materials synergistically toughened by nano-coated particles and silicon carbide whiskers

Nano-coated particles and whiskers were used as reinforcing additives for ceramic tool materials to take advantage of synergistic toughening and enhancement mechanisms. An Al2O3/TiC/CaF2@SiO2/SiCw ceramic tool material was fabricated by hot-pressing. Self-lubricating ceramic tool materials toughened by nano CaF2@SiO2 coated particles and SiC whiskers were studied. When the addition content of nano CaF2@SiO2 coated particles was 10 vol% and the content of SiC whiskers was 20 vol%, ceramic tool materials with the best comprehensive properties were obtained. The results showed that the hardness of the ceramic tool material was 16.52 GPa, the flexural strength was 698 MPa, and the fracture toughness was 6.89 MPa m1/2. Compared with the ceramic tool material with 10 vol% nano CaF2 particles and 20 vol% SiC whiskers, the above properties were improved by 7.06%, 31.74% and 19.06%, respectively. The SiC whiskers played a toughening role, while nano CaF2@SiO2 coated particles reduced the porosity, the compactness and also filled between the grain boundaries of the ceramic tool materials during sintering. This improved the interfacial bonding between ceramic grains, which increased the incidence of transgranular fracture in the ceramic tool materials.

Tuning piezoelectric properties in elastomeric polyurethane nanocomposites utilizing cellulose nanocrystals

AbstractFlexible piezoelectric nanocomposites have been the subject of a lot of recent research due to the development and use of wearable electronic devices and the increasing need for new harvesting devices and sensors due to increasingly intelligent and interconnected cities. In this study, flexible piezoelectric nanocomposites using elastomeric polyurethane (PU) as matrix, and lead zirconate titanate (PZT) as active phase, were produced using cellulose nanocrystals (CNC) as the third phase. The study describes the effect of CNC insertion on the morphology, thermal, electrical, and piezoelectric properties of the nanocomposites. It points out that the CNCs not only act to cause greater dispersion of the ceramic grains in the matrix, but also to lead to greater polarization effectiveness of the ceramic grains, resulting in a longitudinal piezoelectric coefficient (d33) increase of more than 370%, as compared with biphasic composites dependent on the ceramic and nanocrystals content.

Study of the Hydrolytic Stability of Fine-Grained Ceramics Based on Y2.5Nd0.5Al5O12 Oxide with a Garnet Structure under Hydrothermal Conditions.

The hydrolytic stability of ceramics based on Y2.5Nd0.5Al5O12 oxide with a garnet structure obtained by the spark plasma sintering (SPS) method has been studied. The tests were carried out in distilled water under hydrothermal conditions in an autoclave and, for comparison, in a static mode at room temperature. The mechanism of leaching of Y and Nd from the ceramics was investigated. It has been shown that at “low” temperatures (25 and 100 °C), the destruction of pores occured, and the intensity of the leaching process was limited by the diffusion of ions from the inner part of the sample to the surface. At “high” test temperatures (200 and 300 °C), intense destruction of the ceramic grain boundaries was observed. It was assumed that the accelerated leaching of neodymium is due to the formation of grain-boundary segregations of Nd3+ in sintered ceramics.

Strength, plasticity, thermal stability and strain rate sensitivity of nanograined nickel with amorphous ceramic grain boundaries

A large fraction of grain boundaries imparts high strength to nanocrystalline (NC) metals but causes the poor thermal stability of microstructures and a significant reduction of strength with increasing deformation temperature. Stabilizing the microstructure is thus desired. In this work, we self-patterned 1–2 nm thick amorphous ceramic SiOC as grain boundaries in NC Ni with grain size of 13 nm through co-sputtering 75 at.%-Ni and 25 at.%-SiOC, producing Ni-SiOC amorphous ceramic reinforced metals (Ni-SiOC ACRMs) with a core-shell structure. Microscopic characterizations of Ni-SiOC ACRMs before and after 400 °C annealing and after compression deformation confirmed the thermally and mechanically stable core-shell structure. Mechanical properties, such as stress-strain responses and strain rate sensitivity of Ni-SiOC ACRMs over a range of temperatures from room temperature (RT) to 400 °C were measured using in situ micropillar testing in a scanning electron microscope (SEM). We demonstrated that amorphous ceramic SiOC grain boundaries impart a high strength (2.5 GPa at RT and 1.6 GPa at 400 °C), large compressive plasticity (uniform compression strain greater than 35% without shear instability) and thermal stability to Ni-SiOC ACRMs. High strain rate sensitivity (0.015 at RT to 0.042 at 400 °C), small activation volume (about 13b3) and no obvious strain hardening/softening behavior suggest that plastic deformation is accommodated by dislocation slips in Ni grains. Amorphous ceramic grain boundaries act as strong barriers and sinks for impeding and trapping dislocations, strengthening the ACRMs and promoting plastic co-deformation between Ni nanograins and amorphous ceramic grain boundaries; the accumulated dislocations are smeared along the amorphous-crystal interfaces, preventing formation of localized shear bands across multiple nanograins.