Activation Energy For Growth Research Articles

Fine-Grained High-Permeability Fe73.5−xB9Si14Cu1Nb2.5Mx (M = Mo or W) Nanocrystalline Alloys with Co-Added Heterogeneous Transition Metal Elements

This study investigates the effects of multi-transition metals on the soft magnetic properties of Fe73.5−xB9Si14Cu1Nb2.5Mx (M = Nb, Mo, and W) nanocrystalline soft magnetic alloys. Nanocrystalline soft magnetic materials are utilized in electronic components on the basis of their permeability and low core loss. In conventional alloys such as FINEMET, Nb inhibits nanocrystal growth and promotes amorphous formation. In this research, Mo and W were used as additional transition metals to control the size of nanocrystals and explore the potential for enhancing soft magnetic properties. We confirmed that the addition of Mo and W reduced the nanocrystal size, and the activation energy for nanocrystal formation and growth showed significant benefits for nanocrystalline alloys. Consequently, the soft magnetic properties of the alloys containing Mo and W exhibited higher permeability and lower coercivity. These results suggest that multi-transition metals are effective in improving soft magnetic properties by inhibiting nanocrystal formation and growth.

Investigation on Crystallization of CaO‐Al2O3‐B2O3‐BaO Slag Using Differential Scanning Calorimeter and In Situ High‐Temperature Raman Spectroscopy

CaO‐Al2O3‐B2O3‐based slag is among the most promising “nonreactive” mold fluxes for continuous casting of high‐aluminum steel. However, CaO‐Al2O3‐B2O3‐based slag system exhibits a stronger crystallization ability compared to traditional mold fluxes. Herein, calcium oxide in CaO‐Al2O3‐10%B2O3 slag is partially replaced by the same mass of barium oxide (5 and 10 mass%) to adjust the crystallization ability. The crystallization of glassy slags is then investigated using a differential scanning calorimeter and their crystallization kinetics are analyzed using the Matusita–Sakka model. The structural evolution of glassy slags from room temperature to 1200 °C is also investigated using in situ Raman spectroscopy. The kinetic analysis shows that the crystallization process of CaO‐Al2O3‐B2O3‐BaO glassy slags follows the surface crystallization mechanism. The predominant crystalline products are calcium monoaluminate (CaAl2O4) and calcium borate (Ca3(BO3)2). The partial replacement of calcium oxide by barium oxide inhibits the growth of CaAl2O4 in the slag by increasing the activation energy of crystal growth. The high‐temperature Raman spectroscopy study shows that the band between 700 and 900 cm−1 gets weaker relative to the band between 450 and 650 cm−1 at high temperatures. This indicates the strengthening of bending vibration of Al‐O‐Al, which is consistent with the precipitation of CaAl2O4 with full oxygen bridging.

Oxidation of magnesium particles in a fluidized bed reactor

Magnesium is a promising fuel for the metal-enabled cycle of renewable energy and for space power systems. However, the existing methods for combustion of magnesium powders have difficulties with maintaining flame stability. Further, the kinetics and mechanisms of high-temperature oxidation of magnesium powders, needed for combustion modeling, are still not well understood. In the present work, a fluidized bed reactor was used to study the oxidation of spherical magnesium particles in an oxygen/helium environment at temperatures of 530, 550, and 570 °C. The extent of conversion was determined based on the measured oxygen concentration in the exhaust gas. The obtained curves of the extent of conversion and of the conversion rate were analyzed using the Avrami-Erofeev equation and the Mampel-Delmon model. The activation energy obtained with the Avrami-Erofeev equation was 191 or 198 kJ∙mol−1, depending on the dimension (3 or 2, respectively). The Mampel-Delmon approach has shown that the activation energies of nucleation and growth are equal to 189 and 120 kJ∙mol−1, respectively, i.e., the former is virtually the same as the apparent activation energy obtained with the Avrami-Erofeev model at a dimension of 3. With increasing temperature, the rate of nucleation rises faster than the rate of growth. The results obtained with the Mampel-Delmon approach help understand the oxidation mechanism, while the Avrami-Erofeev equation and the obtained apparent activation energy can be used in combustion modeling for simplicity.

Study on the growth mechanism of Pt nanoparticles in oxides: Role of metal-oxide interactions

Strong interactions of metal nanoparticles (NPs) with oxide matrices can dramatically enhance the thermal stability of metal NPs. However, how metal-oxide interactions control the growth of metal NPs remains unclear. Here, the growth of Pt NPs with respect to metal-oxide interactions was investigated by encapsulating them in different Al2O3 and SiO2 oxides. Pt NPs encapsulated in Al2O3 exhibited excellent thermal stability than those in SiO2. Quantitative thermodynamic calculations revealed that metal-oxide interactions strongly governed the driving force for the coalescence of Pt in Al2O3 and SiO2. The kinetic analysis further showed that stronger Pt-Al2O3 interactions controlled the Ostwald ripening of Pt NPs by restricting the diffusion of Pt atoms in oxides, leading to a higher growth activation energy of Pt in Al2O3 than SiO2. These findings explain the different sinter resistance of metal NPs when encapsulated in different oxides, providing valuable insights for enhancing the thermal stability of metal NPs.

Investigating the influence mechanism of aluminum doping amount on the density and grain size of AZO target through phase-field simulation

This study proposes a three-phase model (primary, secondary, and pore phases) utilizing the phase-field method to simulate sintering densification in AZO targets. The impact of secondary phase content and dimensions on the densification of AZO targets was investigated. The findings indicated that the density of the AZO target exhibited an initial increase followed by a subsequent decline with the augmentation of the secondary phase content and size. Conversely, the grain size demonstrated a continuous reduction. The Brook kinetic equation yields activation energies for grain growth of 607.40 kJ/mol, 999.32 kJ/mol, and 1093.20 kJ/mol for 1 wt%, 2 wt%, and 3 wt% Al2O3, respectively. Furthermore, the viability of the model was corroborated through experimentation. Based on the simulation outcomes, AZO targets doped with 2 wt% Al₂O₃ achieved 99.78 % densification, an average grain size of 3.92 μm, and a resistivity of 1.38 mΩ·cm.

Rapid-annealed FeSiBPCu nanocrystalline alloy with high Bs approaching 1.9 T and good bendability

To promote energy savings, high efficiency and miniaturization of power electronic devices, Fe–Si–B–P–Cu nanocrystalline soft magnetic materials with high saturation magnetization (Bs) parallel to that of the 6.5 wt% Si steel and low coercivity (Hc) are desired. In this work, 30 μm-thick Fe84Si3B10P2Cu1 and Fe84.5Si3B9.5P2Cu1 (at.%) amorphous/nanocrystalline precursor ribbons were melt-spun, which has high Fe contents comparable to that of the 6.5 wt% Si steel. These ribbons consist of an amorphous matrix and pre-existing α-Fe of approximately 28–30 nm in size possessed relatively low and similar-value activation energy of nucleation and growth in the range of 224–249 kJ/mol. Which could induce strong crystallization competition and effectively suppress coarsening of the pre-existing α-Fe. The Fe84Si3B10P2Cu1 nanocrystalline alloy obtained by rapid-annealing (∼100 °C/s) the amorphous/nanocrystalline precursor at 480 °C for 30 s (Fe84-480) exhibited a fine and uniform nanostructure containing α-Fe with small average grain size of approximately 23.1 nm and high volume fraction. The Fe84-480 alloy possessed a high Bs of approximately 1.88 T, a low Hc of 8.6 A/m, and good bendability revealed by relatively large bending fracture strain of ∼1.65%, making it a promising soft magnetic material for power electronic devices.

Incorporation of TC4 (Ti-6Al-4V) to construct strong interfacial bonding with Mg matrix to achieve improved hydrogen storage kinetics

Effective contact between the catalyst and the Mg/MgH2 matrix is the key to efficiently enhancing the hydrogen storage kinetics. In this work, a Mg-10 wt% TC4 (Ti-6Al-4V) composite with strong interfacial bonding was prepared by vacuum hot pressing sintering, and the reinforcement mechanism of TC4 was investigated. The results indicated that TC4 has a significant improvement effect on the activation efficiency and hydrogen absorption/desorption kinetics. The hydrogen absorption and desorption activation energies of AZ91-TC4 (53.0/111.3 kJ/mol) are 19.6 and 37.2 kJ/mol lower than that of AZ91 without TC4, respectively. Moreover, TC4 can cause AZ91 to start dehydrogenation at 449 K, and the reduction is about 110 K. Except for the increase of grain boundaries and microcracks caused by TC4, the transition diffusion interface formed by TC4 and Mg matrix with a lower diffusion barrier can be used as a special fast diffusion channel to accelerate the hydrogenation process controlled by H atom diffusion. Meanwhile, the kinetic calculations indicate that the dehydrogenation process of AZ91 is controlled by the nucleation and growth step of Mg, and its nucleation activation energy is ca. 4 times the growth activation energy. TC4 and its induced precipitation of TiAl and Al8Mn5 can dramatically accelerate the nucleation process of Mg, resulting in the rate-determining step changing to the surface penetration of H atoms, and the desorption rate is significantly improved. These positive findings provide new tactics for designing excellent hydrogen storage catalysts.

Bonding mechanism of TC4 titanium alloy/T2 copper vacuum diffusion bonded joint with nickel as transition interlayer

Vacuum diffusion bonding of TC4 titanium alloy (TC4) to T2 copper (T2) using nickel foil as transition interlayer was explored. Ti3Ni, Ti2Ni, TiNi, AlNi2Ti and TiNi3 phases arose at the TC4/Ni bonded interface, and Cu-Ni solid solution appeared in the Ni/T2 interface. Thereinto, AlNi2Ti was a kind of discontinuous nano precipitated phase, which distributed between TiNi and TiNi3 phases. The crystallographic orientations of Ti2Ni, TiNi, AlNi2Ti and TiNi3 phases were (201), (020), (11¯1) and (031), respectively. The interplanar spacing of (031), (11¯1) and (020) was correspondingly d(031) = 0.144 nm, d11¯1 = 0.275 nm and d(020) = 0.137 nm. The lattice mismatch between TiNi3 and TiNi was calculated to be 2.5 %, with low strain energy. The order of effective formation enthalpies for TiNi3, TiNi and Ti2Ni phases formed between titanium and nickel was ∆H′NiTi2 > ∆H′NiTi > ∆H′Ni3Ti. The growth activation energy of TiNi3, TiNi and Ti2Ni phases was correspondingly 35.8 kJ/mol, 180.6 kJ/mol and 347.1 kJ/mol. When welding at 880 °C for 60 min, the highest shear strength of the joints could achieve 150 MPa. The joints fractured along the Ni/T2 interface, the fracture surface of joint was composed of elongated dimples and cellular pits, presenting a shear ductile fracture mode. FCC-Cu, FCC-Ni and (Ni, Cu)ss phases were detected on TC4 and T2 fracture surfaces by XRD. The interdiffusion coefficient ratio of (Ni in Cu)/(Cu in Ni) and (Ni in Ti)/(Ti in Ni) decreased gradually with increasing temperature.

Sintering behavior of alumina by microwave hybrid sintering

Microwave sintering is considered an ideal sintering process due to its rapid heating rate, low energy consumption, and uniform temperature distribution between the interior and surface. However, the difficulty of using a dilatometer and the lack of systematic research have hindered the investigation of activation energy and grain growth kinetics during microwave sintering. In this study, we examined the internal heating mechanism of microwave hybrid sintering, its sintering behavior, and its applicability to commercial processes such as tape casting. The results demonstrated that microwave hybrid sintering reduces the activation energy for both shrinkage and grain growth, confirming the presence of the "microwave effect." This study underscores the potential of microwave hybrid sintering for commercial applications, especially for large ceramic components.

Diffusion behavior and mechanical properties of the Mg-Er binary system

The Mg-Er binary system, as a new lightweight alloy material system with important research value and prospects for development and application, has attracted much attention from researchers in the field of materials science. Studies have shown that the addition of the rare earth element Er can improve the mechanical strength and heat resistance of magnesium alloys. However, the specific mechanism of the interaction between Mg and Er and its effect on the mechanical properties still need to be studied in depth. A combination of microscopic morphology characterization and nanoindentation experiments were employed to investigate the binary diffusion behavior and mechanical properties of the Mg-Er system between 748 K and 823 K in this research. The results indicate that the growth constant of the diffusion layer increases with temperature, with Mg24Er5 exhibiting a higher growth constant than the sum of Mg2Er and MgEr. Notably, the Mg2Er phase has the lowest growth activation energy (127.81 kJ/mol), which suggests that it is formed first during the initial growth stage due to its relatively low energy barrier. Moreover, the interdiffusion coefficient of Mg24Er5 was found to be the highest. By calculating diffusion activation energy, this sequence of formation (Mg2Er→Mg24Er5→MgEr) is in agreement with the trend of growth activation energy. Additionally, nanoindentation experiments and first-principles calculations were utilized to derive the mechanical properties of the Mg-Er binary system. The investigations unveil that Mg2Er boasts the highest hardness and Young’s modulus. These findings have significant implications for understanding the correlation between structure and properties for the Mg-Er alloy system.

Synthesis of Ultrahigh-Purity (6,5) Carbon Nanotubes Using a Trimetallic Catalyst.

Chirality-controlled synthesis of carbon nanotubes (CNTs) is one of the ultimate goals in the field of nanotube synthesis. At present, direct synthesis achieving a purity of over 90%, which can be called single-chirality synthesis, has been achieved for only two types of chiralities: (14,4) and (12,6) CNTs. Here, we realized an ultrahigh-purity (∼95.8%) synthesis of (6,5) CNTs with a trimetallic catalyst NiSnFe. Partial formation of Ni3Sn crystals was found within the NiSnFe nanoparticles. The activation energy for the selective growth of (6,5) CNTs decreased owing to the formation of Ni3Sn crystals, resulting in the high-purity synthesis of (6,5) CNTs. Transmission electron microscopy (TEM) reveals that one-dimensional (1D) crystals of periodic strip lines with 8.8 Å spacing are formed within the as-grown ultrahigh-purity (6,5) CNTs, which are well-matched with the simulated TEM image of closely packed 37 (6,5) CNTs with 2.8 Å intertube distance, indicating the direct formation of chirality-pure (6,5)-CNT bundle structures. The photoluminescence (PL) lifetime increases more than 20 times by the formation of chirality-pure bundle structures of (6,5) CNTs compared to that of isolated (6,5) CNTs. This can be explained by exciton delocalization or intertube excitons within bundle structures of chirality-pure (6,5) CNTs.

Effects of particle size on the crystallization kinetics characterization in CaO–SiO2‐based glass, Part 2: In complex crystallization processes with two or more crystal phases

AbstractBased on the Matusita–Sakka equation and the exothermic peaks in the differential thermal analysis (DTA) curves, in silicate glasses with complex crystallization processes containing the precipitation of two or more crystal phases, the effects of particle sizes on the calculations of crystal growth dimensionality and activation energy of crystal growth have been studied in depth. In crystallization processes with two or more crystal phases but one exothermic peak, 0.3 mm is considered as the boundary between the fine and the coarse particles in this type of glass. For glass samples with a particle size less than 0.3 mm, the crystal growth dimensionality is a three‐dimensional mechanism, and EG increases slightly with decreasing particle size. For glass samples with a particle size greater than 0.3 mm, the crystal growth dimensionality is a two‐dimensional mechanism, and EG increases with decreasing particle size. The EG for the fine‐particle starting material is much lower than that of the coarse‐particle starting material. In crystallization processes with two or more crystal phases and two exothermic peaks, 0.104 mm is considered as the boundary between the fine and the coarse particles in this type of glass raw material. For the first peak, in glass samples with a particle size less than 0.104 mm, the crystal growth mechanism is mainly one‐dimensional growth, and EG increases slightly with decreasing particle size. And for glass samples with particle size greater than 0.104 mm, the crystal growth mechanism is mainly two‐dimensional growth, and EG decreases with decreasing particle size. For the second peak, the crystal growth mechanism is mainly a three‐dimensional growth, and EG increases with decreasing particle size.

Interfacial microstructure and mechanical property of the discontinuous short tungsten fiber-reinforced tungsten matrix composites

For tungsten fiber-reinforced tungsten matrix (Wf/W) composites, the interface between W matrix and W fiber has a dominant effect on the mechanical properties. In this study, the interfacial microstructure in the Wf/W composites with or without Y2O3 coating deposited on W fiber is investigated. The crystal structure of the Y2O3 coating composed of nano-sized columnar grains on the W fibers is cubic. And the crystal structure of Y2O3 coating changes to be face centered cubic after sintering in the Wf/W composites. Two kinds of interfaces, including the interface between W matrix and Y2O3 coating, the interface between W fiber and Y2O3 coating, are present in the Wf/W composites. Different orientation relationships are observed in these two kinds of interface. The stable orientation relationship with 111Y2O3 // 01¯1W have the lowest interfacial energy. The Y2O3 interface is essential for improving the toughening behavior of Wf/W composites and impeding the abnormal grain growth on the surface of W fiber sintering at low temperature. The recrystallization nucleus is developed by the bonding between W powder and W fiber during sintering, and then grow fast into W fiber. The apparent activation energy of abnormal grain growth of W fibers is about 242.7 KJ/mol sintering at temperature between 1500 and 1800 °C. The abnormal large grains usually show intergranular brittle fracture and make the W fiber be brittle.

Tracking microstructural evolution and hardening in Al–Zn–Mg–Cu alloys aged artificially via electrical conductivity measurements

Precipitation hardening, a crucial mechanism for strengthening aluminum alloys, involves stages like Guinier–Preston (GP) zone formation, precipitation, peak aging, and precipitate coarsening. This study focuses on the aluminum 7050 alloy, proposing a method to gauge artificial aging through electrical conductivity measurement. The evolving microstructure and time to peak hardness during aging are vital for creating high-strength alloys. The electrical conductivity variation over time is utilized to analyze the diffusion process governing the clustering and growth of specific phases (η′, η, and S) during artificial aging. The paper demonstrates the impact of GP zones, precipitate formation, and grain growth on electrical conductivity, correlating these factors with hardness, microstructure, and tensile strength to determine the hardening stage. Differential electrical conductivity plots, highlighting aging stages, assist in identifying the hardening phase. Tensile strength and hardness plots differentiate the precipitation phases. The Johnson–Mehl–Avrami–Kolmogorov equation models particle growth kinetics, determining growth rates for AA 7050 alloy. The overall activation energy for precipitate growth is 40.77 kJ/mol, with a growth constant ( m) of ∼4, indicating S phase nucleation during η′ and η growth.

Isothermal β grain growth kinetics and mechanical properties of Ti-351 titanium alloy

The Ti-3.6Al-5.2Mo-4.6Cr-4.7 V-0.7Fe (Ti-351) alloy was developed based on the d-electron theory and the β grain growth behavior during isothermal heat treatment (IHT) was investigated. The nanoindentation analysis of β grain and the tensile properties with different IHT states were carried out. The results showed the grain coarsening temperature of Ti-351 alloy is 850 °C. The grain growth activation energy Q of 75.11–133.92 kJ/mol and the grain growth exponents n of 0.28–0.33 were calculated, indicating a competition between alloy atom diffusion and grain boundary migration. Due to the enhanced diffusion of solute atoms and lower substructure density at higher IHT temperature and longer holding time, the hardness and creep stiffness of β grain would decrease as indicated by nanoindentation test, while the total work W and the plastic deformation work Wp would increase, suggesting an improved toughness of the alloy. In order to achieve full recrystallization of β grains and a better balance between tensile strength and plasticity at room temperature, it is recommended to select a solution heat treatment regime at 850–900 ℃ for 2–4 h.

Revolutionizing ITO waste recycling: Dynamic evolution of ultrafine pulverization and densification

In order to recycle ITO waste targets (R-ITO) efficiently, this study explores the dynamic evolution of ultrafine pulverization of R-ITO particles in jet mills. The R-ITO microparticles obtained by utilizing jet mill pulverization and combining them with the PBM model were used to prepare the R-ITO nano slurry with different average particle sizes with sand milling technology. Furthermore, the R-ITO green compacts were prepared via a pressure-slip casting process. The Brook kinetic model calculated the R-ITO grain growth activation energy to be 570 kJ/mol. Ultimately, the R-ITO target with a relative density of 99.9 % and average grain size of 2.42 μm was attained under a flowing oxygen sintering at 1550 °C for 0.5 h.

Vacuum diffusion bonding of TC4 titanium alloy to T2 copper with VCrNi1.8 eutectic medium entropy alloy interlayer

A new eutectic medium entropy alloy VCrNi1.8 was designed for vacuum diffusion bonding TC4 titanium alloy (TC4) with T2 copper (T2). The influence of welding parameters on the microstructure and shear strength of joints was investigated. β-Ti/Ti3Ni/Ti3AlNi/Ti2Ni/TiNi/TiNi(V, Cr)2/BCC + FCC/Ni(V, Cr)2/Cu phases existed in sequence in the TC4/VCrNi1.8/T2 joint. The crystallographic orientations of Ti3AlNi, Ti2Ni, TiNi and TiNi(V, Cr)2 phases were (200), (020), (011) and (012), respectively. The zone axis of Ti3AlNi, Ti2Ni, TiNi and TiNi(V, Cr)2 phases was correspondingly [002¯], [202], [100] and [4¯00]. The maximum shear strength of joint made at 880 °C for 90 min reached 214 MPa. The growth activation energy of diffusion zones I and II on TC4/VCrNi1.8 side was 230 kJ/mol and 246 kJ/mol, respectively. The interplanar spacing of (200), (020), (011) and (012) was d(200) = 0.656 nm, d(020) = 0.375 nm, d(011) = 0.556 nm and d(012) = 0.225 nm, respectively. The crystal face mismatch of Ti3AlNi/Ti2Ni, Ti2Ni/TiNi and TiNi/TiNi(V, Cr)2 interface was calculated to be 54.5%, 58.3% and 84.8%, respectively, revealing non-coherent with high strain energy. When the bonding temperature increased and holding time prolonged, the joint fractured along the TC4/VCrNi1.8 interface. The fracture morphology of joint presented cleavage fracture characteristics. The average diffusion coefficient of Cu in VCrNi1.8 interlayer at 840 °C, 860 °C, 880 °C, and 900 °C was 0.9 × 10−15 m2/s, 1.2 × 10−15 m2/s,1.6 × 10−15 m2/s, and 2.5 × 10−15 m2/s, respectively.

Effect of TiC particle size on the microstructure and properties of CuCr-TiC composites manufactured by powder metallurgy

Poor thermal stability limits the application of CuCr alloys at high temperatures. In this work, non-stoichiometric TiC particles (7 vol%) reinforced CuCr matrix composites were fabricated. The effects of TiC powders with different particle size (1 μm, 2 μm, 4 μm) on the microstructure and properties were studied. The diffusion of supersaturated Ti atoms induced the formation of Cu (Ti) solid solution transition layer at the interface, which improved the interface bonding. Dislocations caused by thermal mismatch promoted heterogeneous nucleation, which led to the precipitation of coarse Cr clusters. The strength and plasticity of composites increased with the reduction of TiC particle size. Strengthening and fracture mechanisms were discussed, and the strength difference was mainly attributed to thermal mismatch strengthening. Meanwhile, TiC particles refined the matrix grains and improved the activation energy of grain growth. The strength and softening temperature of CuCr alloy were 520 MPa and 540 °C, while that of CuCr-1TiC composite were 530 MPa and 915 °C. CuCr-TiC composites displayed much superior thermal stability than the CuCr alloy. These findings provide practical approaches for developing particle-reinforced copper matrix composites with excellent interfacial bonding and thermal stability.

Recrystallization and grain growth activation energies in a hybrid magnesium material fabricated by high-pressure torsion

The recrystallization and grain growth activation energies of the hybrid AZ31/Mg-0.6Gd (wt.%) alloy were calculated using differential scanning calorimetry analyses and scanning electron microscopy, respectively, after fabricating by high-pressure torsion up to 20 turns and then subjecting to an isochronal annealing treatment from 423 to 723 K for 1 h. The DSC results show one exothermic peak belonging to the static recrystallization of the AZ31 region with an activation energy of 112 ± 10 kJ/mol. The grain growth kinetics for the AZ31 and Mg-0.6Gd regions were described by the Arrhenius equation. The calculation with a grain growth exponent equal to 4 gave values for the activation energies in both the AZ31 (146.2 ± 8.4 kJ/mol) and Mg-0.6Gd (90.9 ± 13.5 kJ/mol) regions. The present results reveal the heterogeneity of the thermal stability of the AZ31/Mg-0.6Gd hybrid material.

Electric field/current enhanced grain growth behavior of 8mol% Y2O3 stabilized cubic ZrO2 (8Y-CSZ) polycrystals

The effect of the flash event on grain growth behavior was examined in 8 mol% yttria-stabilized cubic zirconia (8Y-CSZ) polycrystals under direct and alternating electric fields/currents. Even at the same specimen temperature, the rate of the grain growth is accelerated in the flash event than in the heat treatment without electric field/current (0 V), suggesting that the non-thermal effect caused additionally under the flash event contributes to the acceleration of the grain growth. Although the grain growth behavior can be characterized by the empirical equation (dtn –d0n = kt) with the same grain growth exponent of n = 3 irrespective of the electric field/current, the activation energy for the grain growth is lowered under the flash event. This suggests that the non-thermal effect caused by the flash event does not affect the mechanism of the grain growth, but would accelerate the rate-controlling process of the grain growth. The non-thermal effects can be further accelerated in fine-grained specimens under the alternating current flash and/or by increasing the input power density. Since the grain growth is rate-controlled by the grain boundary cation diffusivity, the non-thermal effect under the flash event would accelerate the grain boundary cation diffusivities through the formation of excess oxygen vacancies depending on the polarity and the power density.