Spinodal Decomposition Research Articles

Evolution of the Microstructure and Mechanical Properties of a Biomedical Ti-20Zr-40Ta Alloy during Aging Treatment

The research focus in the field of medical titanium alloys has recently shifted towards the development of low-modulus and high-strength titanium alloys. In this study, the influence of aging temperature on the microstructure and mechanical properties of a β-type Ti-20Zr-40Ta alloy (TZT) was investigated. It was found that the recovery and the recrystallization occurred in the as-rolled alloy depended on the aging temperature. The periodically distributed Ta-lean phase (β1) and Ta-rich phase (β2) were produced by the spinodal decomposition in all the samples aged at different temperatures. The spinodal decomposition significantly influenced the mechanical properties and deformation mechanisms of the TZT alloy. Upon aging at 650 °C and 750 °C, the as-rolled alloy exhibited a double-yield phenomenon during tensile testing, indicating a stress-induced martensitic transformation; however, its ductility was limited due to the presence of ω phases. Conversely, aging at 850 °C resulted in an alloy with high strength and good ductility, which was potentially attributed to the enhanced strength resulting from modulated structures introduced with spinodal decomposition.

Low-index mesoscopic surface reconstructions of Au surfaces using Bayesian force fields

Metal surfaces have long been known to reconstruct, significantly influencing their structural and catalytic properties. Many key mechanistic aspects of these subtle transformations remain poorly understood due to limitations of previous simulation approaches. Using active learning of Bayesian machine-learned force fields trained from ab initio calculations, we enable large-scale molecular dynamics simulations to describe the thermodynamics and time evolution of the low-index mesoscopic surface reconstructions of Au (e.g., the Au(111)-‘Herringbone,’ Au(110)-(1 × 2)-‘Missing-Row,’ and Au(100)-‘Quasi-Hexagonal’ reconstructions). This capability yields direct atomistic understanding of the dynamic emergence of these surface states from their initial facets, providing previously inaccessible information such as nucleation kinetics and a complete mechanistic interpretation of reconstruction under the effects of strain and local deviations from the original stoichiometry. We successfully reproduce previous experimental observations of reconstructions on pristine surfaces and provide quantitative predictions of the emergence of spinodal decomposition and localized reconstruction in response to strain at non-ideal stoichiometries. A unified mechanistic explanation is presented of the kinetic and thermodynamic factors driving surface reconstruction. Furthermore, we study surface reconstructions on Au nanoparticles, where characteristic (111) and (100) reconstructions spontaneously appear on a variety of high-symmetry particle morphologies.

Structure and thermomechanical properties of superlattice-stabilized TiNbTaZrSiAlN high-entropy coating

Stabilizing the phase structure is the prerequisite for obtaining excellent properties of film materials. Here, we construct a multi-layer superlattice structure including high-entropy sublayer to further tailor the structure and properties of Al-containing nitride coating. A fully cubic structure of Ti0.11Nb0.14Ta0.13Zr0.14Si0.09Al0.39N/Ti0.55Al0.45N (HEN_M) multilayer is realized by stabilizing the cubic/wurtzite-mixed Ti0.11Nb0.14Ta0.13Zr0.14Si0.09Al0.39N (HEN) sublayers with the cubic Ti0.55Al0.45N template layers. The coherent interface strain increases the hardness to 37.5 ± 1.1 GPa for HEN_M in comparison with the corresponding monolithic coatings with 28.2 ± 0.9 GPa for Ti0.55Al0.45N and 22.2 ± 0.7 GPa for HEN. Simultaneously, the HEN_M multilayer shows the optimal Vickers indentation toughness. All coatings exhibit age-hardening characteristics stemming from the spinodal decomposition. Compared to Ti0.55Al0.45N reaching its peak hardness of ∼32.9 ± 0.9 GPa at 900°C, the sluggish diffusion effect promotes HEN and HEN_M maintaining the maximum hardness of ∼25.6 ± 0.8 GPa and ∼39.6 ± 0.9 GPa upon annealing to 1100 and 1000°C, respectively. In addition, exposed to synthetic air at 850°C for 10 h, Ti0.55Al0.45N coating has been completely oxidized, whereas the HEN and HEN_M coatings only experience partial oxidation with oxide scales of ∼1.52 and 0.78 μm.

Insight into annealing-induced hardening and softening behaviors in a laser powder-bed fusion printed in-situ composite eutectic high-entropy alloy

Laser powder-bed fusion (LPBF) printed AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) typically exhibits an in-situ composite structure with an out-of-equilibrium character. Its distinctive hierarchical microstructure implies the potential challenges and opportunities in engineering advanced materials with high performances. Here, an informative overview of the microstructure evolution across various scales and its effect on tensile properties in LPBFed AlCoCrFeNi2.1 subjected to annealing treatments over a wide temperature range is discussed. Microstructural observations indicate that spinodal decomposition within the B2 lamellae becomes evident after annealing at 500 °C, marked by a pronounced compositional fluctuation of Cr. Annealing the sample at 600 °C leads to the precipitation of BCC nanoparticles through structural disordering of Cr-rich regions within the modulated nanostructure. Tensile tests and strengthening models reveal that the annealing-induced hardening responses are largely associated with precipitation strengthening resulting from the ordering strengthening of L12 nanoprecipitates and the coherency and modulus strengthening of BCC nanoprecipitates, as well as the spinodal hardening from modulated nanostructure. Notably, BCC precipitation strengthening plays a crucial role in enhancing the strength of the annealed alloys. A strong precipitation strengthening effect is realized due to the coarsening of the BCC and L12 nanoprecipitates at 600 °C, and the strengthening effect from BCC precipitates gradually weakens as their dissolution at 650 °C, resulting in abnormal hardening behavior. Upon annealing at higher temperatures (700–1000 °C), phase decomposition, precipitation dissolution, even recrystallization occur sequentially, resulting in varying degrees of softening behaviors.

Strengthening complex concentrated alloy without ductility loss by 3D printed high-density coherent nanoparticles

Metallic 3D printing enables fast fabrication of net-shaped components for broad engineering applications, yet it restrains the use of most mechanical processing methods for strengthening alloys, e.g. forging, rolling, etc. Here, we proposed a new strategy for enhancing the strength of 3D printed complex concentrated alloys without losing ductility. This strategy relies on the rapid cooling of 3D printing to achieve a supersaturation state that is beyond conventional casting. Then, spinodal decomposition via aging is exploited to introduce high-density coherent nanoparticles for strengthening. The proposed strategy is demonstrated in a 3D printed Cu-based complex concentrated alloy. The rapid solidification during printing strongly inhibits elemental diffusion, leading to a high supersaturation state. High-density nanoparticles with coherent interface and size of ∼7 nm are introduced into the 3D printed samples through spinodal decomposition via simple aging treatment. The strength of the 3D printed alloy is increased by 30% after aging with no ductility loss, leading to a strength-ductility combination superior to other Cu alloys. This strategy is readily applicable to other spinodal alloys fabricated by 3D printing for circumventing the strength-ductility trade-off dilemma.

Thermodynamic assessment of two-step nucleation occurrence in supercritical fluid

For the crystallization of an API in supercritical CO2, a two – step nucleation mechanism involves the apparition of metastable liquid droplets in the vapour phase composed of the API dissolved in the CO2, before crystallization. To find out the pressure and temperature conditions such a two – step mechanism could be observed, we studied the stability / metastability / instability for {(S)-Naproxen + CO2} and {(RS)-Ibuprofen + CO2} vapour binary mixtures. Thermodynamic computations proposed in the paper, have shown that a mixture of API and CO2 at elevated pressures can be unstable and/or metastable with respect to a liquid-vapour equilibrium and at the same time with respect to a solid-vapour equilibrium. Depending on the degree of supersaturation, such a mixture can potentially first decompose via spinodal decomposition into coexisting liquid and vapour phases, which turn due to nucleation and growth theory to a solid-fluid equilibrium.

Size effects on spinodal decomposition

Abstract We examine the influence of grains size on the stability of polycrystalline coherent binary solid solutions. By assuming that the grains are isotropic, we find that the tendency for instability decreases as the radius of the grains decrease. We also find that a temperature-dependent critical grain radius exists below which the tendency for instability vanishes and the grains are stable, with respect to infinitesimal composition fluctuations, for any initial composition. We find that the critical grain radius decreases monotonically as the temperature decrease. If the radius of the grains is smaller than the minimum critical grain radius the grains are stable for any temperature and initial composition.

Near-critical dark opalescence in out-of-equilibrium SF6

The first-order phase transition between the liquid and gaseous phases ends at a critical point. Critical opalescence occurs at this singularity. Discovered in 1822, it is known to be driven by diverging fluctuations in the density. During the past two decades, boundaries between the gas-like and liquid-like regimes have been theoretically proposed and experimentally explored. Here, we show that fast cooling of near-critical sulfur hexafluoride (SF6), in presence of Earth’s gravity, favors dark opalescence, where visible photons are not merely scattered, but also absorbed. When the isochore fluid is quenched across the critical point, its optical transmittance drops by more than three orders of magnitude in the whole visible range, a feature which does not occur during slow cooling. We show that transmittance shows a dip at 2eV near the critical point, and the system can host excitons with binding energies ranging from 0.5 to 4 eV. The spinodal decomposition of the liquid-gas mixture, by inducing a periodical modulation of the fluid density, can provide a scenario to explain the emergence of this platform for coupling between light and matter. The possible formation of excitons and polaritons points to the irruption of quantum effects in a quintessentially classical context.

Engineering Mixing Properties of Fluids by Spatial Modulations.

We propose a method to change the effective interaction between two fluids by modulation of their local density distributions with external periodic potentials, whereby the mixing properties can be controlled. This method is applied to a mixture of dilute bosonic gases, and binodal and spinodal curves emerge in the phase diagram. Spinodal decomposition into a mixed-bubble state becomes possible, in which one of the coexisting phases has a finite mixing ratio. A metastable mixture is also realized, which undergoes phase separation via nucleation.

Pattern dynamics of density and velocity fields in segregation of fluid mixtures.

We present comprehensive numerical results from a study of model H, which describes phase separation kinetics in binary fluid mixtures. We study the pattern dynamics of both density and velocity fields in d = 2, 3. The density length scales show three distinct regimes, in accordance with analytical arguments. The velocity length scale shows a diffusive behavior. We also study the scaling behavior of the morphologies for density and velocity fields and observe dynamical scaling in the relevant correlation functions and structure factors. Finally, we study the effect of quenched random field disorder on spinodal decomposition in model H.

Effect of warm rolling and heat treatment on heterogeneous austenite morphology and tensile property of 3Mn steel

Facing the current lack of clarity in temperature selection mechanisms for warm rolling in medium Mn steel, three warm rolling methods were conducted in 3Mn steel according to the rolling temperatures in the dual-phases region or ferrite region. Subsequently, the effect of heat treatment on the austenite morphologies and tensile properties of warm-rolling samples was studied. Rolling in dual-phase regions (750 °C) led to heterogeneous austenite morphology composed of equiaxed and lamellar grains while rolling in the ferrite region (600 °C) resulted in significant cementite precipitation and the absence of retained austenite. Warm rolling promoted the formation of dislocation cells in the lath-like grains, and they did not evolve into grain boundaries completely because low deformation temperature didn’t trigger the complete dynamic recrystallization. Tempering after rolling provided a significant enhancement in plasticity through the enrichment of C and Mn in austenite and the formation of multiple heterogeneous austenite morphologies with equiaxed, coarse lath-like and fine lamellar grains. In addition, superlattice structures in the matrix are formed through the formation of stacking fault networks and the spinodal decomposition. Ultimately, the exceptional properties were achieved in 3Mn steel, with an ultimate tensile strength of 1409 MPa and a total elongation of 27.3 %.

Solidification and tribological behaviors of CoCrFeNiSi0.5-(Al,Ti) non-equiatomic high entropy alloy coatings fabricated by direct laser deposition

In order to evaluate the difference in the effects of Al and Ti elements on the microstructure and tribological behaviors of CoCrFeNi-based high entropy alloy (HEA) coatings, CoCrFeNiSi0.5-(Al,Ti) non-equiatomic HEAs coatings were prepared using direct laser deposition (DLD). The phase constitution, solidification microstructure and tribological behaviors of the HEA coatings were investigated. The results indicated that CoCrFeNiSi0.5 HEA coating was composed of face centered cubic (FCC) phase with microstructure of columnar and cellular grains. The addition of Al and Ti led to a columnar-to-equiaxed transition (CET) in the HEA coatings. When only Al was added (CoCrFeNiSi0.5Al0.5), the primary phase transformed into a body centered cubic (BCC) phase (94 vol%). Additionally, Cr3Si formed in the interdendrite (ID) region, and a spinodal decomposition structure emerged in the dendrite (DR) region. Conversely, with the inclusion of Ti alone (CoCrFeNiSi0.5Ti0.5), the matrix maintained its FCC phase, but Ni16Ti6Si7 (G phase, 20.9 vol%) and Cr15Co9Si6 (15.1 vol%) were generated in the ID and DR regions, respectively. Incorporating both Al and Ti (CoCrFeNiSi0.5Al0.5Ti0.5) significantly reduced the G phase content in the ID region to 7.9 vol% and led to the formation of dispersed Fe3Al nanoparticles with an average size of 99 nm in the DR region. The CoCrFeNiSi0.5 HEA coating exhibited the lowest hardness (249 HV0.1), the highest friction coefficient (0.778), and the poorest wear resistance. For the HEA coatings containing Al and Ti, the microhardness significantly increased to over 700 HV0.1, and the friction coefficient decreased to around 0.6. However, the wear resistance of the CoCrFeNiSi0.5Al0.5 HEA coating was almost equivalent to that of the CoCrFeNiSi0.5 with a wear loss of 5.1 mg. By contrast, the HEA coatings containing Ti demonstrated notably improved wear resistance, with wear losses of only 2.2 mg and 2.4 mg for the CoCrFeNiSi0.5Ti0.5 and CoCrFeNiSi0.5Al0.5Ti0.5 HEA coatings, respectively.

Engineering Interconnected Open-Porous Particles via Microfluidics Using Bijel Droplets as Structural Templates.

Designing porous structures is key in materials science, particularly for separation, catalysis, and cell culture systems. Bicontinuous interfacially jammed emulsion gels represent a unique class of soft matter formed by kinetically arresting the separation of the spinodal decomposition phase, which is stabilized by colloidal particles with neutral wetting. This study introduces a microfluidic technique to create highly interconnected open-porous particles using bijel droplets stabilized with hexadecyltrimethylammonium bromide (CTAB)-modified silica particles. Monodisperse droplets comprising a hydrophobic monomer, water, ethanol, silica particles, and CTAB were initially formed in the microfluidic device. The diffusion of ethanol from these droplets into the continuous cyclohexane phase triggered spinodal decomposition within the droplets. The phase-separated structure within the droplets was stabilized by the CTAB-modified silica particles, and subsequent photopolymerization yielded microparticles with highly interconnected, open pores. Moreover, the influence of the ratio of the CTAB and silica particles, fluid composition, and microchannel direction on the final structure of the microparticles was explored. Our findings indicated that the phase-separated structure of the particles transitioned from oil-in-water to water-in-oil as the CTAB/silica ratio was increased. At intermediate CTAB/silica ratios, microparticles with bicontinuous structures were formed. Regardless of the fluid composition, the pore size of the particles increased with time after phase separation. However, this coarsening was arrested 15 s after droplet formation in the CTAB-modified silica particles, accompanied by a change in the particle shape from spherical to ellipsoidal. In situ observations of the bijel droplet formation revealed that the particle shape deformation is caused by the rolling of elastic bijel droplets at the bottom of the microchannel. As such, the channel setup was altered from horizontal to vertical to prevent the deformation of bijel droplets, resulting in spherical particles with open pores.

Hydrogen promoted Ti3Al precipitation during Ti-6Al-4V martensite tempering

Temporary hydrogen alloying (THA) treatments are extensively used to refine coarse Ti-6Al-4V microstructures. The present study focuses on a THA treatment which promotes martensite decomposition; it highlights the effect of hydrogen on tempered martensite evolution by comparing martensite decomposition in hydrogenated and control samples. Microstructure evolution was characterised using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS). Bulk XRD measurements indicate that quenching hydrogenated Ti-6Al-4V from the beta region causes a partial beta to hexagonal (α’) plus orthorhombic (α’’) martensite transformation. The EBSD, TKD and HRTEM analyses show that hydrogen saturated plate martensite decomposes to form a nanobanded structure which consists of nanosized, periodical Al-rich, and V-rich HCP regions that stabilise D019 Ti3Al within 3 h of tempering. In comparison, typical martensite decomposition is observed in the control experiment. Quenching non-hydrogenated Ti-6Al-4V from the beta region causes a full beta to hexagonal (α’) martensite transformation. Elemental partitioning occurs, but not to the extent that D019 Ti3Al is promoted and compositional banding is not observed. Formation of the nanobanded structure suggests that hydrogen altered the transformation pathway in hydrogenated martensite because of the presence of α’’possibly promoting spinodal decomposition.

On the divergent effects of stress on the self-organizing nanostructure due to spinodal decomposition in duplex stainless steel

Duplex stainless steels suffer from serious embrittlement due to the self-organization of the nanostructure caused by phase separation (PS) in ferrite. As duplex stainless steel (DSS) components are often subjected to stress during service, the effect of elastic tensile stress (ETS) on phase separation (PS) in alloy 2507 has been investigated in this study. The alloy was aged at 400 and 450 °C for different times under an applied ETS. The nanostructure evolution and mechanical properties were analyzed using small-angle neutron scattering and analytical transmission electron microscopy as well as Vickers-hardness and nanoindentation measurements. The results show that the applied ETS can suppress spinodal decomposition (SD) in ferrite in DSS 2507, which may be due to that ETS increases the critical compositional fluctuation wavelength for SD and thus increases the diffusion distance and barrier to the occurrence of SD. The suppressive effect is more obvious at longer aging time for the same level of applied stresses. It is also indicated that the suppressive effect of ETS seems to change non-monotonically with stress levels and the medium stress level is likely to have the largest suppressive effect. The suppressive effect of ETS on PS may significantly delay the embrittlement and extend the service longevity of DSS components within the miscibility gap. These results further the understanding of the effect of ETS on PS and elastic stress should be considered in the configurations of computational simulations of PS and evaluation of the service longevity of DSS components.

Spinodal decomposition and phase separation in polar active matter.

We develop and study the hydrodynamic theory of flocking with autochemotaxis. This describes large collections of self-propelled entities all spontaneously moving in the same direction, each emitting a substance which attracts the others (e.g., ants). The theory combines features of the Keller-Segel model for autochemotaxis with the Toner-Tu theory of flocking. We find that sufficiently strong autochemotaxis leads to an instability of the uniformly moving state (the "flock"), in which bands of different density form moving parallel to the mean flock velocity with different speeds. This instability is, therefore, completely different from the well-known "banding instability," in which bands form perpendicular to the mean flock velocity. The bands we find, which are reminiscent of ant trails, coarsen over time to reach a phase-separated state, in which one high-density and one low-density band fill the entire system. The same instability, described by the same hydrodynamic theory, can occur in flocks phase separating due to any microscopic mechanism (e.g., sufficiently strong attractive interactions). Although in many ways analogous to equilibrium phase separation via spinodal decomposition, the two steady-state densities here are determined not by a common tangent construction, as in equilibrium, but by an uncommon tangent construction very similar to that found for motility-induced phase separation of disordered active particles. Our analytic theory agrees well with our numerical simulations of our equationsof motion.

Freezing-mediated formation of supraproteins using depletion forces

HypothesisLong-acting formulations such as microparticles, injectable depots and implantable devices can realize spatiotemporally controlled delivery of protein drugs to extend their therapeutic in vivo half-lives. To efficiently encapsulate the protein drugs into such drug delivery systems, (sub)micron-sized protein particles are needed. The formation of micronized supraproteins can be induced through the synergistic combination of attractive depletion forces and freezing. The size of the supraproteins can be fine-tuned from submicron to several microns by adjusting the ice crystallization rate through the freeze-quench depth, which is set by the target temperature.MethodsSupraprotein micron structures were prepared from protein solutions under various conditions in the presence and absence of nonadsorbing polyethylene glycol. Scanning electron microscopy and dynamic light scattering were employed to determine the sizes of the supraproteins and real-time total internal reflection fluorescent microscopy was used to follow the supraprotein formation during freezing. The protein secondary structure was measured before and after micronization by circular dichroism. A phase diagram of a protein–polyethylene glycol mixture was theoretically predicted to investigate whether the depletion interaction can elucidate the phase behavior.FindingsMicronized protein supraparticles could be prepared in a controlled manner by rapid freeze-drying of aqueous mixtures of bovine serum albumin, horseradish peroxidase and lysozyme mixed with polyethylene glycol. Upon freezing, the temperature quench initiates a phase separation process which is reminiscent of spinodal decomposition. This demixing is subsequently arrested during droplet phase separation to form protein-rich microstructures. The final size of the generated protein microparticles is determined by a competition between phase separation and cooling rate, which can be controlled by target temperature. The experimental phase diagram of the aqueous protein–polyethylene glycol dispersion aligns with predictions from depletion theory for charged colloids and nonadsorbing polymers.

The evolution of the demixing morphology in quasi 2D water-lutidine mixtures: a fractal dimension analysis

In this work, the evolution of the morphological properties of the liquid-liquid phase separation process of water-lutidine mixtures in a quasi-2D geometry locally heated by laser absorption is studied at different heating rates by videomicroscopy and complemented by a finite element simulation. Morphological changes of the separated domains are characterised using the fractal dimension and the distribution of domain sizes, capturing the main steps of the process: spinodal decomposition derived from the fluctuations in density at the critical point, separation into a bicontinuous structure, breaking of the structures producing a wide distribution of sizes, and the subsequent growth and coalescence of the demixed regions (domains) to produce a complete separation. A comparison with the simplest case of typical nucleation is made by performing the same analysis at a concentration where critical fluctuations are not present. We conclude that the methodology presented here can be used to characterise the main steps of the phase separation process and distinguish between spinodal decomposition and nucleation.

Fine-Tuning Melt Pools and Microstructures: Taming Cracks in Powder Bed Fusion—Laser Beam of a non-weldable Ni-base Superalloy

Powder Bed Fusion – Laser Beam (PBF-LB) of high γ’ strengthened Ni-base superalloys, such as CM247LC, is of great interest for high temperature applications in gas turbines. However, PBF-LB of CM247LC is challenging due to the high cracking susceptibility during PBF-LB processing (solidification cracking) and heat treatment (strain age cracking, mostly caused by residual stresses). This study focuses on understanding the impact of process parameters on microstructure, residual stresses and solidification cracking. Laser power (P), speed (v) and hatch spacing (h) were varied while the layer thickness (t) was fixed. The melt pool size and shape were found to be key factors in minimizing solidification cracking. Narrower and shallower melt pools, achieved using a low line energy density (LED = P/v ≤ 0.1 J/mm), gave low crack densities (0.7 mm/mm2). A tight hatch spacing (h = 0.03 mm) resulted in reduced lack of fusion porosity. Electron backscatter diffraction investigations revealed that parameters giving finer microstructure with 〈100〉 crystallographic texture had low crack densities provided they were processed with a low LED. Atom probe tomography elucidated early stages of spinodal decomposition in the as-built condition, where Cr and Al cluster separately. The extent of spinodal decomposition was found to be affected by the LED and the hatch spacing. Samples with low LED and small hatch spacing showed higher degrees of spinodal decomposition. X-ray diffraction residual stress investigations revealed that the residual stress is proportional to the volumetric energy density (VED = P/(v. h. t)). Although low residual stresses can be achieved by using low VED, there is a high risk of lack of fusion. Hence, other parameters such as modified scan strategy, build plate pre-heating and pulsed laser mode, must be further explored to minimize the residual stresses to reduce the strain age cracking susceptibility.

Micron-Sized Thiol-Functional Polysilsesquioxane Microspheres with Open and Interconnected Macropores: Preparation, Characterization and Formation Mechanism.

Polysilsesquioxane (PSQ) microspheres have shown promise in many fields, but previous studies about porous PSQ microspheres are scarce. Herein, we fabricated novel micron-sized thiol-functional polysilsesquioxane (TMPSQ) microspheres with open and interconnected macropores by combining inverse suspension polymerization with two-step sol-gel and polymerization-induced phase separation processes, without using phase-separation-promoting additives or sacrificial templates. The chemical composition of the TMPSQ microspheres was confirmed using FTIR and Raman spectroscopy. The morphology of the TMPSQ microspheres was characterized using SEM and TEM. TGA was employed to test the thermal stability of the TMPSQ microspheres. Mercury intrusion porosimetry and nitrogen adsorption-desorption tests were performed to investigate the pore structure of the TMPSQ microspheres. The results showed that the TMPSQ microspheres had open and interconnected macropores with a pore size of 839 nm, and the total porosity and intraparticle porosity reached 70.54% and 43.21%, respectively. The mechanism of porous generation was proposed based on the morphological evolution observed using optical microscopy. The macropores were formed through the following four steps: phase separation (spinodal decomposition), coarsening, gelation, and evaporation of the solvent. The macropores can facilitate the rapid mass transfer between the outer and inner spaces of the TMPSQ microspheres. The TMPSQ microspheres are promising in various fields, such as catalyst supports and adsorbents.