Phase Particles Research Articles

Microstructural Evolution and Tensile Properties of Al-Si Piston Alloys during Long-Term Thermal Exposure

The present study investigated microstructural evolution and changes in tensile properties of an Al-Si piston alloy subjected to thermal exposures at 250 and 350 °C for 150, 300, and 500 h. Microstructural and nanoscale precipitates were characterized using a combination of high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) images and scanning electron microscopy (SEM). The tensile testing was performed. The results demonstrated that the thermal exposure induced granulation of the δ-Al3CuNi particles, alongside precipitation of the θ-Al2Cu phase particles and AlCu clusters within the matrix. Specifically, an increase in the size and number density of the θ-Al2Cu phase particles was observed with exposure time at 250 °C. Conversely, at 350 °C, the θ-Al2Cu particles exhibited a gradual increase in size with prolonged thermal exposure, coupled with a decrease in their number density. AlCu clusters precipitated solely at a thermal exposure temperature of 350 °C, with precipitation intensifying over time. Moreover, a decrease in the alloy’s tensile strength and an increase in elongation were noted after thermal exposure. Finally, the present study discussed the precipitation mechanisms of θ-Al2Cu particles and AlCu clusters within the grains, suggesting that the AlCu clusters exerted a more effective strengthening effect compared to the θ-Al2Cu particles.

Study on the mechanism of second phase formation in high-purity fused silica materials for semiconductor application

Gas bubble is a common defect in high-purity fused silica materials, but the formation of the second phase particles related to gas bubble and its mechanism remain unclear till now. In this work, we have presented a method for characterization of colored gas bubbles in high-purity fused silica crucibles for Czochralski silicon by the means of TEM and EDX. Based on it, the origin of the coloring of the gas bubbles is demonstrated to be induced by the gathering of Fe impurity and then, the formation of high-density second phase—ferric oxide (Fe2O3) crystals around the gas bubbles. Moreover, our results provide insight into the formation mechanism of second phase crystals which can be induced by stress field variations around gas bubbles during the cooling process that probably promoted by volume shrinkage effect and increasing solubility of gas from gas bubbles into fused silica substrate. The understanding of the second phase particle formation mechanism in high-purity fused silica materials is valuable for its further controlling.

Viscoelastic-plastic transition of polyamide/hydrogenated nitrile blends based on Ostwald’s ripening mechanism and its effect on mechanical and tribology properties

The controllable preparation of the phase separation structure of platic/elastomer blends is very important to improve the mechanical properties of materials. In this paper, polyamide 1212/hydrogenated nitrile (PA1212/HNBR) blends were prepared by melt-compounding method. During the mechanical testing, a novel viscoelastic–plastic transition behavior was observed. The addition of polyamide 1212 could effectively reinforce mechanical and frictional properties of HNBR matrix. It was worth noting that 30 wt% PA1212 content was the critical value of viscoelastic–plastic transition of the blends. Meanwhile, the tribological performance of the blends was also decayed at the critical point (i.e. 30 wt% PA1212). Therefore, the uniformly dispersed particle phase structure formed via Ostwald’s ripening mechanism was crucial to the improvement of tribological performance. In addition, the large-scale production of platic/elastomer blends with high-performance can be realized through this controllable preparation technique.

Insight into the Hot Corrosion Behavior of FeMnCrSi/TiC Coatings at 900 °C

This study explores the deposition of an Fe-MnCrSi/TiC coating on 45 steel surfaces using high-velocity arc spraying technology, examining the microstructure and hot corrosion behavior of the resultant layer. The microstructure of the FeMnCrSi/TiC coating primarily consists of an α-Fe (BCC) solid solution, composed of Fe, Mn, Cr, Si, C, and other elements, with a minor presence of β-Fe (FCC) solid-solution phase and unmelted TiC particles. Following 100 h of cyclic 900 °C hot corrosion, Mn on the coating surface preferentially oxidizes, forming a manganese-rich oxide layer. This process reduces the oxygen partial pressure (O2) within the coating, prompting the formation of a dense Cr2O3 layer on the inner side of the oxide layer. Concurrently, the rapid diffusion of Mn and Cr elements triggers the generation of Mn- and Cr-deficient regions at the metal/oxide layer interface, inducing the transformation of the coated metal primary matrix from an FCC + BCC dual phase to an α-Fe (BCC) single phase. After the reaction, the hot corrosion weight gain of the coating reached 12.43 mg/cm2, approximately one-fourteenth of the weight gain of the 45 steel substrates. This weight gain adheres to the parabolic law, suggesting that the FeMnCrSi/TiC coating exhibits excellent corrosion resistance under the given conditions.

Viscosity and structure studies of iron-based quaternary melts: The effect of P

This study systematically investigates the underlying principles and mechanisms governing viscosity across the entire range for the Fe-4.5C-0.1Ti-xP (in wt.%) melts. The viscosity profile exhibits distinct variations in different phases. In the solid–liquid transition region, the primary determinant of viscosity is the presence of solid phase particles, while in the region characterized by liquid phase, the primary influencing factor is the number of clusters. Notably, the impact of P content demonstrates a contrasting effect on low-temperature solid phase precipitation and high-temperature liquid phase structure. During the low-temperature solid phase precipitation stage, an increase in P content serves as a catalyst for graphite precipitation, resulting in an increase in system viscosity and, by extension, impacting an increase in system viscosity. In contrast, within the high-temperature liquid phase, the interaction of P with iron (Fe) results in the breakdown of mid-range clusters in the original system, leading to the formation of smaller clusters with a reduced overall cluster volume. Consequently, an increase in P content is associated with a decrease in viscosity. These findings provide a nuanced understanding of the interplay between P content and viscosity throughout different phases of the melt.

Trajectory Tracking Control Design for 4WS Vehicle Based on Particle Swarm Optimization and Phase Plane Analysis

With the rapid development of today’s society, the traffic environment has become more and more complex. As an essential part of intelligent vehicles, trajectory tracking has attracted significant attention for its stability and safety. It is prone to poor accuracy and instability in extreme working conditions like high speed. In this paper, a trajectory tracking control strategy to ensure lateral stability at a high speed and low attachment limit conditions is proposed for distributed drive vehicles. The model predictive controller (MPC) was used to control the front wheel angle, and the particle swarm optimization (PSO) algorithm was designed to optimize the MPC control parameters adaptively. The sliding mode controller controls the rear wheel angle, and the vehicle instability degree is judged by analyzing the β − β˙ phase plane. The controllers of different instability degrees are designed herein. Finally, a torque divider is designed to consider the actuation anti-slip. The designed controller is verified by Carsim and MATLAB-Simulink co-simulation. The results show that the trajectory tracking controller designed in this paper effectively improves the tracking accuracy under the premise of ensuring stability.

A Eulerian Monte Carlo method for the numerical solution of the multivariate population balance equation

Statistical descriptions of particulate phases and granular media based on the notion of a property distribution are particularly advantageous for dense, many-particle dispersions since they support the direct evaluation of Eulerian property statistics, permit a kinematically simple treatment of particle collisions and feature a model complexity that is independent of the number of physical particles. On the minus side, the property distribution is governed by a high-dimensional population balance equation (PBE) whose moment reduction is accompanied by a challenging closure problem and engenders intricate dynamical nonlinearities. Circumventing both the curse of dimensionality and the moment closure problem, we present a Eulerian Monte Carlo (EMC) solution method that harnesses a representation of the property distribution in terms of an ensemble of property samples and is based on a statistical enforcement of the spatially and temporally discretized PBE. After application of a kinetic finite volume scheme, the PBE is subjected to a fractional steps decomposition that separates spatial transport from transport in property space. Conceptually, spatial transport is emulated by assembling the ensemble in one spatial grid cell from samples drawn from the ensembles in neighbouring cells at the previous time point. In this regard, we propose a two-level sampling scheme that is sensitive to large-scale features of the marginal velocity distribution and effectively reduces the instantaneous sampling error. The property transport step, by contrast, is based on the method of characteristics and involves the propagation of individual samples as property characteristics in time. While the sampling error afflicting the property statistics needs to be controlled using a top-level time or ensemble averaging, the EMC method remains well-conditioned for an arbitrary number of samples, is easy to implement and involves a computational expense that scales only linearly with the number of particle properties. Based on two benchmark examples, we analyze the spatial and statistical convergence properties of the EMC method and demonstrate its capacity to capture multiple crossings of particle trajectories. A third example involves the two-way coupled transport of size-polydispersed inertial particles in an inhomogeneous flow field.

Insight into the Fe-rich phases strengthening mechanisms of non-heat-treatable Al-Mg-Mn-Fe-Cu alloys

This paper examines the effect of Fe addition on the microstructure characterized by scanning electron microscopy/electron backscattered diffraction, neutron diffraction, and synchrotron X-ray tomography and the mechanical properties of Al-Mg-Mn-Fe-Cu alloys. The findings reveal that the microstructures of the alloys consisted of an Al matrix, Al6(FeMn), and Al2CuMg phase particles. The addition of Fe significantly increased the yield strength (YS), and ultimate tensile strength (UTS) of the alloys, while reducing elongation. The transformation of the 3D morphology of the Al6(FeMn) phase from separated and fine particles with Chinese-script morphology to interconnected rod-like structure as Fe content increased from 0.1 % to 0.8 %. This strengthening effect was attributed to the slip lines being blocked at the vicinity of the interconnected Fe-rich phase, leading to grain rotation and dislocation density increment around the Fe-rich phase, ultimately improving the strength of the alloys. However, the Fe-rich phases and Al2CuMg phases were found to be prone to cracking under tensile stress, resulting in decreased elongation of the alloys. This study provides a potential application in the design and manufacturing of new non-heat-treatable Al alloys for the automotive industry.

Synthesis and coating properties of (La0.5Eu0.25Y0.25)2Zr2O7 ceramic powder

The (La0.5Eu0.25Y0.25)2Zr2O7 (LEYZ) ceramic powder for spraying was prepared and synthesised by combining spray granulation and solid phase reaction phase, and a double ceramic layer structure with (La0.5Eu0.25Y0.25)2Zr2O7 ceramic surface coating and YSZ intermediate coating was prepared by atmospheric plasma spraying. Experimental characterisation revealed that the moulding state of spray granulated powders was significantly influenced by the solid content. When the solid content is small, the viscosity of the slurry is insufficient, and the prepared powder has poor formability and small overall particle size. When the solid content is large, the slurry is too viscous, which easily leads to unfavourable conditions such as sticky walls. The best formability of the pelletised powder was obtained with a solid content of 55 wt-% and a binder content of 2.0 wt-%. Compared with La2Zr2O7 (LZ) ceramics, the fracture toughness of the rare-earth co-doped modified LEYZ ceramic coating was increased by 8.4% and the bond strength was increased by 49.9%, showing good toughness and crack resistance. Moreover, LEYZ coating has significantly better resistance to solid phase particle erosion than LZ coating, with 46.3% and 45.4% reduction in erosion rate at 45° and 90°, respectively.

Nitroaromatic compounds in six major Chinese cities: Influence of different formation mechanisms on light absorption properties

Nitroaromatic compounds (NACs) are important nitrogen organics in aerosol with strong light-absorbing and chemically reactive properties. In this study, NACs in six Chinese megacities, including Harbin (HB), Beijing (BJ), Xi'an (XA), Wuhan (WH), Chengdu (CD), and Guangzhou (GZ), were investigated for understanding their sources, gas-particle partitioning, and impact on BrC absorption properties. The concentrations of ΣNACs in PM2.5 in the six cities ranged from 9.15 to 158.8 ng/m3 in winter and from 2.02 to 9.39 ng/m3 in summer. Nitro catechols (NCs), nitro phenols (NPs), and nitro salicylic acids (NSAs) are the main components in ΣNACs, with NCs being dominant in particulate phase and NPs being dominant in the gas phase. Correlation analysis between different pollutant species revealed that coal and biomass combustions were the major sources of NACs in the northern cities during wintertime, while secondary formation dominated NACs in the southern cities during summertime. The contribution of ΣNACs to brown carbon (BrC) light absorption ranged from 0.85 to 7.98 % during the wintertime and 2.07–6.44 % during the summertime. The mass absorption efficiency at 365 nm (MAE365) were highest for 4-nitrocatechol (4NC, 17.4–89.0 m2/g), 4-methyl-5-nitrocatechol (4M5NC, 15.0–76.9 m2/g), and 4-nitroguaiacol (4NG, 11.7–59.8 m2/g). The formation of NCs and NG through oxidation and nitration of catechol and guaiacol led to a significant increase in aerosol light absorption. In contrast, NPs and NSAs formed by the photonitration and photooxidation in liquid phase showed high polarity but low light absorption ability, and the proportions of (NPs + NSAs) in the light absorption of ΣNACs were lower than 15.3 % in the six megacities.

Co-precipitation mechanism of Cu-rich phase and κ-carbide precipitates in Fe-28Mn-10Al-1C-3Cu austenitic low-density steel

The excellent comprehensive properties of Fe-28Mn-10Al-1C-3Cu austenitic low-density steel are related to its main precipitates of Cu-rich phase and κ-carbide particles. The co-precipitation mechanism of Cu-rich phase and κ-carbide particles in Fe-28Mn-10Al-1C-3Cu austenitic low-density steel are investigated. Adding Cu to Fe-28Mn-10Al-1C austenitic low-density steel can promote the precipitation of κ-carbide. The κ-carbide can also promote the precipitation of Cu-rich phase with FCC structure. The κ-carbide preferentially precipitate compared to Cu-rich phase. The κ-carbide and Cu-rich phase have a cube-on-cube orientation relationship with the austenitic matrix: [110]γ//[110]κ//[110]Cu and (111)γ//(111)κ//(111)Cu.

Implementing moving object capability in a two-phase Eulerian model for sediment transport applications

This article presents the validation of a modified 6DoF solver which includes the contribution of particle forces on rigid objects. The solver is an extension of sedFoam, employed for a wide range of sediment transport applications. The first validation consists in a simple case of a sphere freely falling in a pure fluid. Then, the same sphere is submerged in a fluid with suspended particles. The next step involves placing a granular bed under the sphere to study its arrest due to particle-particle interactions. Lastly, the trajectory of a cylinder immersed in a uniform granular flow is studied to emphasize the lift and drag forces exerted by the particle phase on the solid object. Results show that overSedDyMFoam accurately reproduces experimental/numerical measurements successfully capturing the behavior of solid objects subjected to granular and fluid forces. This implementation is a significant step towards understanding complex interactions between fluid, particles, and structures.

Enhancement of the magnetic property of Nd-Fe-B sintered magnets through novel powder rounding modification

Two types of sintered Nd-Fe-B magnets were fabricated by the process of powder metallurgy technology through two different powder preparation processes i.e., conventional powder preparation process and novel powder rounding modification. The microstructure, composition and properties of the two type powders have been studied including the particle size distributions and flowabilities. Furthermore, magnetic properties, microstructure and alignment degree of the magnets prepared by the corresponding powder also have been investigated. The novel powder rounding modification rounds the sharp edges and corners of the particles compared to the conventional powder preparation process, thereby reducing friction between the particles and improving flowability of the powder. As a result, the alignment degree of the sintered magnet is enhanced, which contribute to the improvement of the remanence and the energy product density. The powder that experienced rounding process changed the distribution of RE (rare earth)-rich particles, causing tiny RE-rich particles to adhere around the main phase particles, facilitating the compact of bulk during liquid-phase sintering process and achieving uniform distribution of RE-rich phases around the Nd2Fe14B main phase, resulting in increasing the magnet density and coercivity. As a consequence, we have produced the magnet with Br = 1.43 T, Hcj = 1049 kA/m and (BH)max = 393.2 kJ/m3, which is fully superior to conventional magnet with Br = 1.41 T, Hcj = 969 kA/m and (BH)max = 383.7 kJ/m3 by adopting powder rounding process. This indicates that the novel powder rounding modification is an efficient approach for synchronous improvement of magnetic performance of sintered Nd-Fe-B without any heavy rare earth elements.

Rheological and tribological properties of seaweed powders as thickeners for liquid foods

Thickened liquid foods are particularly interesting in culinary applications and the management of swallowing disorders. Polysaccharide molecules and suspended soft particles play a major role in increasing viscosity and mouthfeel. In this work, tribo-rheological effects of finely ground particles (less than 75 μm) of Durvillaea antarctica seaweed (SP) as a minimally processed and natural alternative to commercial thickeners were studied. Shear viscosity (η), viscoelastic moduli (G′, G″), and the coefficient of friction (CoF) were determined for SP dispersions, using as controls two commercial thickeners: modified maize starch-based (TE) and xanthan gum-based (TU). SP and SP dispersions were characterized microstructurally and evaluated at concentrations of 1.2%, 2.4%, and 4.8% w/v, with and without artificial saliva (AS). SP dispersions exhibited a pseudoplastic behavior in the range of shear rates 0.1–100 s−1 and viscoelasticity (G’>G”) in the 0.1–80 rad/s frequency range. The incorporation of AS had a dilution effect in SP and TU dispersions, but additionally, in the case of TE, a hydrolyzing effect decreased the values of the responses. In the tribology experiments, all samples followed a Stribeck curve. SP dispersions were more lubricating than AS and controls in the physiological range of velocities during oral processing and swallowing (e.g.,>100 mm/s). The thickening, viscoelastic, and lubrication behavior of SP dispersions were attributed to the soluble solids released from the SP (37%–51% d. w.) and interactions with ghosts of SP particles in the continuous aqueous phase. Fine seaweed particles may be a sustainable and low-cost alternative to commercial thickeners in some food applications.

Achieving high strength and uniform ductility in high-entropy alloys via dynamic-precipitation accelerated transformation-induced plasticity

This study presents a novel approach to fabricating advanced transformation-induced plasticity (TRIP) high-entropy alloys (HEAs) that exhibit an exceptional combination of high strength and uniform ductility, far surpassing the mechanical performance of previously developed TRIP HEAs and non-TRIP multiphase HEAs. The ultrafine-grained Al5Cr20Fe35Co35Ni5 TRIP HEA sample exhibits a yield strength of gigapascal-level, ranging from 1100 to 1260 MPa, with large uniform elongations that range from 29 % to 39 %. Simultaneously, the alloy displays outstanding toughness, reaching 46,000±5390 MPa·%. The achievement of this significant breakthrough rests upon two key factors: (1) achieving an ultrafine-grained FCC matrix in a fully recrystallized microstructure with the aid of thermally induced B2 phase, and (2) dynamic precipitation of nanometer-sized B2 phase particles on high-density stacking faults and slip bands created within the interiors of ultrafine grains. The dynamic precipitation of the B2 phase, facilitated by the formation of an amorphous phase that serves as a precursor to the B2 crystalline phase, is a rare occurrence in HEAs at room temperature. This dynamic precipitation process greatly enhances TRIP-assisted strain hardening (from FCC to HCP phase) of the current alloy at ultrafine grains, enabling the overcoming of the inherent tensile ductility constraints typically associated with ultrafine-grained metals. The current development of TRIP HEAs with an outstanding combination of high strength and high toughness is believed to mark a remarkable milestone in the application field of TRIP HEAs.

Evolution of Zr(Fe,Cr)2 second phase particles in Zircaloy-2 under heavy ion irradiation

The Zr(Fe,Cr)2 second phase particles (SPPs) found in Zircaloy-2 and -4 are known to amorphize and dissolve under irradiation. In the present work, their evolution has been studied in situ in a transmission electron microscope (TEM) under 600 keV Ar2+ irradiation at 320°C, taking samples to two different doses of 13 and 24 dpa. Using scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDX), the samples were thoroughly characterised before and after irradiation, allowing subtle changes in precipitate chemistry to be detected. At both doses the SPPs were fully amorphous, with an accompanying release of Fe to the surrounding matrix. The Fe/Cr ratio was seen to decrease in the SPP core and increase at the interface with the matrix, a result of ballistic mixing across the interface coupled with outward diffusion of Fe. No alignment of dislocation loops or segregation of solute to defects in the matrix was observed, although Fe was found to diffuse further along the c-axis direction compared to the a-axis direction.

Enhanced mechanical properties of thermo-mechanically affected zone of friction-stir welded AZ61 magnesium alloy joint

Friction-stir welded (FSW) magnesium alloy joints frequently fracture at thermo-mechanically affected zone (TMAZ), and the joints exhibit unsatisfactory welding efficiency and ductility. The TMAZ is considered as the weakest region of the entire joint. Enhance the mechanical properties of TMAZ can improve the performance of the welded joint. In this work, subsequent aging treatment and pre-strain of 3% along the weld seam were conducted on the FSW AZ61 magnesium alloy joint. The microstructure of the TMAZ is characterized by abundant nanoscale second phase particles and {10–12} twins. The reduced basal texture intensity decreased the anisotropy of plastic deformation. The welded joint showed a good synergic of welding efficiency (96%) and ductility (20%). The enhanced strength is attributed to the blocking effect of nanoscale particles and grain/twin boundaries to dislocation movement. The increasing of twin boundaries is the main reason for the improvement of work hardening ability and ductility during tensile deformation. This work demonstrated that introducing {10–12} twins and nanoscale particles into TMAZ is an effective way to improve the balance of strength and ductility of the welded joint due to the synergistic effect of multiple strengthening and toughening mechanisms.

Comparative Study of Catalytic Activity of Recyclable Au/Fe3O4 Microparticles for Reduction Of 2,4-Dinitrophenol and Anionic, Cationic Azo Dyes.

We synthesized Au/Fe3O4 microparticles. Initially, citrate-capped Fe3O4 micro-sized particles were synthesized by the co-precipitation method with an excess amount of trisodium citrate. Gold ions were reduced on the surface of citrate-capped Fe3O4 and grew as gold sub-microparticles with an average diameter of 210 nm on the surface. The characteristic SPR peak of gold nanoparticles on the surface of Fe3O4 was detected at 584 nm, whereas the absorption in the near-infrared region was increased. SEM images has proved that the synthesized Au/Fe3O4 composite microparticles has an average diameter of 1.7 micrometers. The results of XRD patterns proved the existence of both crystal phases of Fe3O4 and Au particles. To investigate the catalytic activity, the reaction rate constant of reduction of 2,4-dinitrophenol (2,4-DNP) and degradation of Congo red (CR), and methylene blue (MB) with NaBH4 in the presence of Au/Fe3O4 catalyst was monitored by UV-Vis spectroscopy. The initial reaction rate constant calculated from the change in characteristic peak absorptions of 2,4-dinitrophenol was 3.97×10-3 s-1, while the reaction rate constants for the degradation of CR and MB were 9.72×10-3 s-1 and 14.25×10-3 s-1 respectively. After 5 cycles, Au/Fe3O4 microparticles preserved 99 % of the reaction rate constant, exhibiting considerable recycling efficiency in the reduction of nitro groups.

Modeling PAH Mixture Interactions in a Human In Vitro Organotypic Respiratory Model.

One of the most significant challenges in human health risk assessment is to evaluate hazards from exposure to environmental chemical mixtures. Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous contaminants typically found as mixtures in gaseous and particulate phases in ambient air pollution associated with petrochemicals from Superfund sites and the burning of fossil fuels. However, little is understood about how PAHs in mixtures contribute to toxicity in lung cells. To investigate mixture interactions and component additivity from environmentally relevant PAHs, two synthetic mixtures were created from PAHs identified in passive air samplers at a legacy creosote site impacted by wildfires. The primary human bronchial epithelial cells differentiated at the air-liquid interface were treated with PAH mixtures at environmentally relevant proportions and evaluated for the differential expression of transcriptional biomarkers related to xenobiotic metabolism, oxidative stress response, barrier integrity, and DNA damage response. Component additivity was evaluated across all endpoints using two independent action (IA) models with and without the scaling of components by toxic equivalence factors. Both IA models exhibited trends that were unlike the observed mixture response and generally underestimated the toxicity across dose suggesting the potential for non-additive interactions of components. Overall, this study provides an example of the usefulness of mixture toxicity assessment with the currently available methods while demonstrating the need for more complex yet interpretable mixture response evaluation methods for environmental samples.

Effect of internal phase particle size on properties of site mixed emulsion explosive at plateau environment

To study the effect of internal particle size on the microstructure properties and thermal decomposition characteristics of site mixed emulsion explosive at different altitudes. Site mixed emulsion explosive was prepared with different shear rate. The particle size, viscosity, sensitized bubbles, detonation velocity and peak pressure of the emulsion explosive were tested after stored at different simulated altitudes. The thermal decomposition characteristics of emulsion matrix prepared at three different rotational speeds were measured by thermogravimetric analyzer and kinetic analysis was performed by non-isothermal model Kissinger–Akah–Sunose (KAS) method. The results show that with the increase in altitude, the internal phase size showed a trend of first increasing and then decreasing, and the number of sensitized bubbles within the emulsion explosive decreases. At an altitude of 0 m, the detonation velocity and peak overpressure of the emulsion explosive prepared by 1600 r min−1 increased 4.78% and 29.09%, respectively compared with 1200 r min−1, and at an altitude of 4500 m, the detonation velocity increased 11.87%, the peak overpressure increased 43.98%. The thermal decomposition activation energy of the emulsion matrix at 1600 r min−1 increased 13.14% compared to 1200 r min−1. It shows that in the production of site mixed emulsion explosive at high altitude, reducing the particle size of the internal phase of emulsion explosives in a certain range can effectively improve the performance of emulsion explosives.