Microstructural Defects Research Articles

Anomalous size effects of ultra-small graphene sheets on the thermal properties of macroscopic films

Graphene films assembled from graphene nanosheets have achieved a wide range of applications in thermal management due to their ultra-high thermal conductivity. Although it is well established in the micron range that increasing the lateral size of graphene sheets enhances the thermal conductivity of graphene films. However, the preparation of large-size graphene sheets and their assembly into ordered film structures remain challenging, which impedes the development of high-performance thermally conductive graphene films. Herein, by unifying the properties of graphene sheets and preparation processes, we correlate the thermal conductivity of graphene films and the lateral size of starting sheets ranging from 0.32 to 20.32 μm and probe the underlying mechanism from the perspectives of macroscopic and microscopic structural defects. Surprisingly, decreasing lateral size to 0.32 μm achieved as high in-plane thermal conductivity (K//, 1550.06 ± 12.99 W/mK) and significantly higher through-plane thermal conductivity (K⊥, 8.11 ± 0.08 W/mK) of graphene films as the case of 20.32 μm. Besides, the commonly overlooked size effect of K⊥ shows an unexpected negative correlation, and the size effect of K// is also not monotonically increasing. These phenomena are correlated with micro-structure defects and lattice defects. Mechanism analysis reveals that thermally induced gas generation and the complex gas-sheet interactions during micro-structure evolution play a critical role in the size effect and may explain the unexpected negative size effect in the sub-micro range. These findings in size effects provide theoretical guidance for the selection of raw materials in fabricating highly thermally conductive graphene films.

Fabrication of a Low-Cost Fused Filament Fabrication-based 3D Printer and Investigation of the Effect of Process Parameters on Mechanical Properties of 3D-Printed Samples

Additive Manufacturing (AM) techniques add material layer-by-layer to fabricate parts or products, compared to subtractive manufacturing processes, where the material is removed to obtain the final product. The most common method among AM techniques is fused filament fabrication (FFF), which uses filament material to print objects into end products. The present study's aims include designing and fabricating a custom FFF-based 3D printer and investigating the effects of three process parameters on the tensile properties of the 3D-printed samples. Initially, the 3D printer was successfully fabricated. The locally fabricated 3D printer uses Marlin Firmware 2.0 as programming code to control different functionalities of the printing processes. After fabrication and calibration, the printer 3D-printed a few samples successfully. Moreover, a design of experiments plan was formulated to print tensile specimens based on the levels of the process parameters. Tensile testing was performed, and the analysis of variance (ANOVA) confirmed that the process parameters significantly affected the tensile strength. The effects of the process parameters were then analyzed, along with the defect formation and microstructure analysis. Finally, optimum parameters for printing PLA parts with better tensile properties were figured out for the designed 3D printer.

Quantification of microscale factors for fatigue failure in NiTi shape memory alloys

Fatigue behavior is intrinsically linked to microstructural alterations induced by cyclic loading. However, the quantification of microstructural defects associated with fatigue damage of NiTi shape memory alloys (SMAs) is lacking, which hinders the development of a physically based fatigue criterion. To this end, a multi-scale experimental analysis was conducted on cyclically deformed NiTi SMAs, which evidenced a strong correlation between microstructural inhomogeneity and localized deformation behavior. The microstructural change associated with fatigue was quantified in terms of stored strain–energy, with the highest values observed in the regions where fatigue cracks initiate. Consequently, stored energy is deemed as an effective fatigue indicator, offering valuable insights for future work in the design and optimization of SMAs’ structures against fatigue.

Analysis of abnormal bright band characteristics of forging for a new low-cost titanium alloy

A centimeter-scale defective microstructure, namely abnormal bright band characteristics (ABBC), is found in engineering production of titanium alloy forgings, and it seriously affects the stability and reliability of performance. The targeted work for the reason of the formation of the ABBC is carried out in this paper. The ABBC contains a large number of small colony α, without grain boundary. The α phase in the ABBC includes 12 variants from one β grain. The crystallographic orientation of reconstructed β phase in the ABBC is a standard cube texture. The formation of the ABBC is caused by the abnormal grain growth (AGG) of cube-grain. The cube-grain is a low energy storage grain, which can merge with other grains to grow rapidly.

Comparative Study of Multilayer Hard Coatings Deposited on WC-Co Hardmetals

This paper examines the impact of a multilayered gradient coating, applied via plasma-activated chemical vapor deposition (PACVD), on the structural and mechanical attributes of nanostructured WC-Co cemented carbides. WC-Co samples containing 5 and 15 wt.% Co were synthesized through a hot isostatic pressing (HIP) process using nanoparticle powders and coated with two distinct multilayer coatings: titanium nitride (TiN) and titanium carbonitride (TiCN). Nanosized grain formation without microstructural defects of the substrates, prior to coating, was confirmed by magnetic saturation and coercivity testing, microstructural analysis, and field emission scanning electron microscope (FESEM). Nanoindentation, fracture toughness and hardness testing were conducted for uncoated samples. After coatings deposition, characterizations including microscopy, surface roughness determination, adhesion testing, coating thickness measurement, and microhardness examination were conducted. The impact of deposited coatings on wear resistance of produced hardmetals was analyzed via scratch test and dry sliding wear test. Samples with higher Co content exhibited improved adhesion, facilitating surface cleaning and activation before coating. TiN and TiCN coatings demonstrated similar roughness on substrates of identical composition, suggesting Co content’s minimal influence on layer growth. Results of the mechanical tests showed higher microhardness, higher elastic modulus, better adhesion, and overall superior tribological properties of the TiCN coating.

Identification of structural defects and their impact on the magnetic memory, static and cyclic strength of VNS9-SH thin sheet trip-steel

Identification of microstructure defects, which are stress concentrators (SC) during the operation of mechanical engineering products, is an important scientific and practical task relevant for manufacturing enterprises. This problem becomes especially urgent and difficult for critical helicopter parts made of sheet TRIP steel VNS9-Sh (23Kh15N5AM3-Sh) and operating under cyclic loads due to the complex microstructure of the steel and small thickness of strips and sheets. To assess the impact of structural defects on the cyclic strength of products made of the steel under study, the specimens were preliminary sorted proceeding from the results of their testing using the method of metal magnetic memory (MMM) and metallographic studies. The MMM method is a structure-sensitive procedure which provides information about the presence of structural defects that arise during the manufacture. Magnetic anomalies in the form of sharp local changes in the intrinsic stray magnetic field (SSMF) (H) and its gradient |ΔH| along the length of the controlled section Δx, were identified on the surface of sheets cut from five different batches. A conventional classification of the identified anomalies was made according to the magnitude of the magnetic field gradient. The specimens of two types were cut in zones of magnetic anomalies and outside them: type 1 — for cyclic tests and type 2 — for metallographic studies. The geometric parameters and field gradient values of magnetic anomalies on specimens of type 1 and type 2 were the same. Metallographic studies in zones of maximum magnetic field gradient on type 2 specimens revealed defects in the form of a strip at the boundary of different structures, which is a structural stress concentrator (SSC) and a source of the inhomogeneity and changes in the magnetic properties. Type 1 specimens with similar magnetic anomalies and Type 1 specimens cut from sheets outside zones of magnetic anomalies were then selected for cyclic testing. Comparative tests for cyclic strength of the specimens with and without specified SSC were carried out. It is shown that the presence of SSC zones in the specimens reduces the number of cycles to failure during cyclic tests by 1 – 2 orders of magnitude compared to the specimens free of SSC. Based on cyclic tensile tests of specimens, a limiting value of the magnetic field gradient was determined that corresponds to the acceptable level of stress concentration on structural defects. This value is recommended for use as a rejection criterion when examining a new tape by the MMM method.

Densification mechanisms during high-pressure sintering of nanocrystalline Gd2Zr2O7 ceramic

High-pressure sintering (HPS) is a promising technique for producing nanocrystalline ceramics with unique properties. However, the densification mechanisms of HPS for nanocrystalline ceramics at different sintering stages remain controversial. This study focuses on Gd2Zr2O7 (GZO) nanocrystalline ceramics, investigating their microstructure evolution and densification behavior under varying pressures, temperatures, and dwelling times. The HPS process involves distinct stages: cold compaction, hot compaction, and isothermal progression. During cold compaction, densification is driven by the breakdown of aggregates, particle rearrangement, and local plastic deformation, resulting in a relative density of 84.8 %. The intermediate stage achieves an increase to ∼93.7 % in relative density by grain boundary-mediated plastic deformation mechanism. The final isothermal stage, held at 500 °C/5 GPa, achieves nearly full density (∼99.2 %) through diffusion creep, eliminating microstructural defects. This comprehensive understanding of HPS densification mechanisms, exemplified by GZO ceramics, contributes to advancing nanocrystalline ceramic applications.

Non‐Fluorinated Ethers to Mitigate Electrode Surface Reactivity in High‐Voltage NCM811‐Li Batteries

AbstractLithium (Li) metal batteries (LMBs) with nickel (Ni)‐rich layered oxide cathodes exhibit twice the energy density of conventional Li‐ion batteries. However, their lifespan is limited by severe side reactions caused by high electrode reactivity. Fluorinated solvent‐based electrolytes can address this challenge, but they pose environmental and biological hazards. This work reports on the molecular engineering of fluorine (F)‐free ethers to mitigate electrode surface reactivity in high‐voltage Ni‐rich LMBs. By merely extending the alkyl chains of traditional ethers, we effectively reduce the catalytic reactivity of the cathode towards the electrolyte at high voltages, which suppresses the oxidation decomposition of the electrolyte, microstructural defects and rock‐salt phase formation in the cathode, and gas release issues. The high‐voltage Ni‐rich NCM811‐Li battery delivers capacity retention of 80 % after 250 cycles with a high Coulombic efficiency of 99.85 %, even superior to that in carbonate electrolytes. Additionally, this strategy facilitates passivation of the Li anode by forming a robust solid‐electrolyte interphase, boosting the Li reversibility to 99.11 % with a cycling life of 350 cycles, which outperforms conventional F‐free ether electrolytes. Consequently, the lifespan of practical LMBs has been prolonged by over 100 % and 500 % compared to those in conventional carbonate‐ and ether‐based electrolytes, respectively.

Non-Fluorinated Ethers to Mitigate Electrode Surface Reactivity in High-Voltage NCM811-Li Batteries.

Lithium (Li) metal batteries (LMBs) with nickel (Ni)-rich layered oxide cathodes exhibit twice the energy density of conventional Li-ion batteries. However, their lifespan is limited by severe side reactions caused by high electrode reactivity. Fluorinated solvent-based electrolytes can address this challenge, but they pose environmental and biological hazards. This work reports on the molecular engineering of fluorine (F)-free ethers to mitigate electrode surface reactivity in high-voltage Ni-rich LMBs. By merely extending the alkyl chains of traditional ethers, we effectively reduce the catalytic reactivity of the cathode towards the electrolyte at high voltages, which suppresses the oxidation decomposition of the electrolyte, microstructural defects and rock-salt phase formation in the cathode, and gas release issues. The high-voltage Ni-rich NCM811-Li battery delivers capacity retention of 80 % after 250 cycles with a high Coulombic efficiency of 99.85 %, even superior to that in carbonate electrolytes. Additionally, this strategy facilitates passivation of the Li anode by forming a robust solid-electrolyte interphase, boosting the Li reversibility to 99.11 % with a cycling life of 350 cycles, which outperforms conventional F-free ether electrolytes. Consequently, the lifespan of practical LMBs has been prolonged by over 100 % and 500 % compared to those in conventional carbonate- and ether-based electrolytes, respectively.

Structure and corrosion properties of multilayer metal/nitride/oxide ceramic coatings formed on austenitic-martensitic steel by magnetron deposition

The design of protective coatings preventing the degradation and failure of austenitic steels in humid climate is a relevant issue. In this work, a conventional magnetron sputtering method was utilized in order to fabricate a four-layer Ni/Al-Si-N/Ni/Al-Si-O coating onto austenitic-martensitic steel. At the first stage of deposition, a three-layer coating was formed in an Ar+N2 atmosphere using a mosaic target (Ni or Al-Si), while the second stage included the deposition of the outer ceramic Al-Si-O layer in an Ar+O2 gas mixture. The studies of the structure, hardness, adhesion strength and electrochemical behavior (in 3.5 wt.% NaCl) of the «coating/steel» system were performed by means of X-ray Diffraction, electron microscopy, mechanical (indentation and scratch) tests and electrochemical impedance spectroscopy. The ceramic Al-Si-O layer exhibits an amorphous structure. The adjacent nickel layers have submicrocrystalline columnar grains. The ceramic Al-Si-N layer possesses a nanocrystalline columnar structure based on AlN + Si3N4 phases. Hardness behavior of the multilayer coating varies nonmonotonically due to a contribution of the soft amorphous phase in the upper surface layer and high-strength nanocrystalline phases in the underlying sublayers. It has been revealed that as-deposited multilayer coating decreases a corrosion rate of the substrate. The layered structure of the coating hinders the transport and diffusion of chloride ions to the substrate and decreases the corrosion rate of the substrate. However, a transport of chloride ions into the inner layers of the coating may occur through the microstructural defects preserved in the amorphous Al-Si-O layer. The scheme describing an initiation of corrosion damage and formation of corrosion products under critical corrosion conditions was proposed.

How are microstructural defect interactions linked to simultaneous intergranular and transgranular fracture modes in polycrystalline systems?

The major objective of this investigation is to fundamentally understand and predict how intergranular (IG) and transgranular (TG) fracture modes nucleate and propagate in f.c.c. polycrystalline systems due to defects, such as total and partial dislocation densities and grain boundary (GB) structures and misorientations. A dislocation density crystalline plasticity (DCP) formulation based on the evolution and interaction of total and partial dislocation densities was integrated with a recently developed fracture approach to investigate the fracture nucleation and propagation of simultaneous multiple fracture events, including both IG and TG fracture events. The aggregate grains and GB orientations and morphologies are based on EBSD measurements that are representative of polycrystalline copper aggregates with a broad range of random high angle and low angle GBs. The predictions indicate that dislocation density pileups induce IG fracture due to interrelated stress, slip, and total and partial dislocation density accumulations and interactions for both high angle GBs (HAGBs) and low angle GBs (LAGBs). TG fracture nucleation and propagation occurred due to normal stress accumulations, which exceeds the fracture stress, along cleavage planes. Furthermore, it is shown how IG cracks transition from the GB plane to the cleavage planes as cracks nucleate and propagate. Accumulated plastic zones due to different slip system activities can impede and blunt crack propagation and fronts. These plastic zones form due to high Lomer and Shockley partial dislocation densities. These predictions, which are consistent with experimental observations, provide a fundamental understanding of how simultaneous failure modes initiate and propagate for physically representative microstructures.

VHCF behavior and defect tolerance of modified bainitic 100Cr6 with a high retained austenite content

Since the fatigue life of high strength steels, e.g., roller bearing steel 100Cr6, depends on microstructural defects, an improvement of their defect tolerance can enhance the performance of components. To improve the defect tolerance, the retained austenite content can be increased. Thus, in this work the high cycle and very high cycle fatigue behavior of two modified laboratory variants of 100Cr6, which have an increased content (1.5 wt%) of Al and Si, respectively, were analyzed since these alloying elements lead to higher fractions of austenite. Moreover, an industrially available variant with 0.6 wt% Si was analyzed as a reference. All steels were investigated in the bainitic condition and had austenite contents of about 20 vol-%. However, the distribution and chemical composition of the austenite differed. The presented results demonstrate that the effect of retained austenite on defect tolerance is caused by i) the increased ductility and ii) the local deformation-induced phase transformation. To strengthen the effects of the austenitic phase, a finer distribution as well as a lower austenite stability are useful. Consequently, to evaluate the effect of retained austenite on the fatigue behavior the content, the distribution and the chemical composition of the austenitic phase must be considered.

Effect of SHS powder processing on structure formation and optical transmittance of MgO–Y2O3 composite ceramic

Extending the transparency range of MgO–Y2O3 composite ceramic to wavelength less than 3 μm is highly desirable, as it broadens their potential applications in infrared (IR) optics. This study illustrates the effectiveness of deagglomerating a mixture of magnesium oxide and yttrium sesquioxide powders, derived from self-propagating high-temperature synthesis (SHS), in achieving this goal. The impact of powder deagglomeration on the microstructure and porosity defects of hot-pressed MgO–Y2O3 ceramic was analyzed using electron and IR microscopy. The results showed that the deagglomeration enhanced the homogeneity of the composite grain mixture, slowed down the grain growth, suppressed the formation of large grains, and significantly reduced the number of porosity microdefects in the material. The optical transmittance increased from 42 % to 77 % at a wavelength of 2 μm (for samples with a thickness of 1.2 mm) when deagglomerated powders were used, compared to non-deagglomerated ones.

Dual sinter-aids to fabricate high-entropy transition metal carbide ceramic and their properties

Due to excellent performances and easy adjustability, more and more researchers pay attention to high-entropy ceramics, which can be applied in many fields. In this work, a high-entropy transition metal carbide ceramic, (Hf0.2Ta0.2Zr0.2Nb0.2W0.2)C, was fabricated by pressureless sintering method. To obtain highly dense ceramic, dual sintering aids (Cr3C2 and C), are employed in the sintering process. Owing to suitable microstructure (grain size and defect density), the ceramics exhibit excellent electric conductivity(0.7040 MS/m) and flexural strength (378 ± 11.4 MPa). Meanwhile, the relationship between electromagnetic shielding effectiveness and different aid content in the X-band is also investigated. The P3 ceramic with a thickness of 1 mm can achieve an EMI shielding efficiency of 92 dB in the X-band as a result of the stronger interface polarization and relaxation effects. High-entropy ceramic obtained in this work would give a different way to fabricate shielding material and can promote the use of high-entropy ceramics as effective EMI shielding materials.

Nanostructuring and oxygen-vacancy tuning to repress thermal transport and activate thermoelectric properties of green-synthesized ZnO

We introduce eco-friendly synthesized ZnO nanoparticles by using orange peel extract for thermoelectric applications. Orange peel extract plays a crucial role as a reducing and surface-stabilizing agent in the synthesis process. It significantly affects the microstructure and lattice defects governing transport properties and thermoelectric performance of polycrystalline ZnO. A comparison of the structural and thermoelectric properties between the green-synthesized ZnO (ZnO OPE) and commercial ZnO (ZnO com) is conducted. The outcomes indicate that the ZnO OPE sample exhibits a 3.5-time higher electrical conductivity than the commercial ZnO at 1073 K, which is thermally activated at more than 673 K by oxygen vacancies. Moreover, the highly porous nanostructure of the ZnO OPE sample substantially reduces thermal conductivity from 14.5 W/mK to 5.5 W/mK with increasing temperature from 300 to 1073 K. The combination of nanostructure and defect modification paves the way for thermoelectric ZnO-based materials synthesized using environmentally friendly processes.

Microstructure, solidification defects and mechanical properties of high-modulus and high-strength SiC/AlSi10Mg composites fabricated by selective laser melting

Since the aluminum matrix composites prepared by additive manufacturing are prone to defects such as pores and cracks, the properties of the formed composites cannot be further improved. Therefore, the preparation of SiC/AlSi10Mg composites with high modulus and high strength by selective laser melting technology is of great significance for the wide application of aluminum matrix composites. This work will further investigate the defect formation, microstructure evolution, and solidification mechanism of the composites. The matrix microstructure of the composites can be efficiently refined by adding SiC. In addition, the 5 wt.% SiC/AlSi10Mg composites showed improvements in the tensile yield strength, microhardness, bending strength, elastic modulus, and ultimate tensile strength as compared to the AlSi10Mg alloy. These increases were 21.1 %, 18 %, 8.7 %, 23.2 % and 9.2 % respectively. The strengthening mechanisms at room temperature include fine grain strengthening, thermal mismatch strengthening, solid solution strengthening and precipitation strengthening. It is also mentioned that the primary causes of the decrease in toughness are stress concentration and the existence of the brittle precipitation phase (Al4C3). The increase in high-temperature strength is attributed to the pinning role of SiC and precipitate phases relative to grain boundary and dislocation climbing.

Enhancing mechanical properties and defects elimination in 2024 aluminum alloy through interlayer friction stir processing in wire arc additive manufacturing

In this study, a hybrid wire arc additive manufacturing (WAAM) and interlayer friction stir processing (IFSP) approach was utilized to enhance the quality of 2024 aluminum alloy components. The defects characteristic, microstructure evolution, and mechanical properties of the fabricated components and after T6 heat treatment were analyzed systematically. Our analysis reveals that IFSP can break and dissolve the eutectic phases, significantly reduce porosity defects and refine the grain size of the as-deposited materials, thus improving the overall mechanical properties. Notably, compared to the WAAM as-deposited component, the yield strength (YS) and ultimate tensile strength (UTS) in the top-layer stir zone (SZ) of IFSP component increased from 154 ± 3 to 267 ± 2 MPa, and from 258 ± 12 to 360 ± 3 MPa, respectively. However, in the middle-layer SZ, S-phase precipitation and coarsening induced by thermal cycling during additive manufacturing slightly reduced the tensile properties. Post-T6 heat treatment led to uniformly distributed properties in the IFSP component along both horizontal and vertical directions, with the YS, UTS, and elongation (EL) averaging 353 ± 9 MPa, 470 ± 4 MPa, and 10.5 ± 1.6%, closely matching those of wrought counterparts. The significant improvements in mechanical properties are primarily attributed to the elimination of porosity and precipitation of fine needle-like S-phase. This research not only demonstrates the potential of IFSP in enhancing the mechanical properties of WAAM-fabricated 2024 aluminum alloy but also offers a promising technique for producing high-quality components suitable for high-performance aerospace applications.

Influence of heat treatments on low-power-LPBFed CuCrZr for nuclear fusion applications

In this study, the processability of CuCrZr alloy with additive manufacturing (AM) technology and the performance achievable with Direct Age Hardening treatments for nuclear fusion applications were investigated. This copper alloy is one of the most interesting for the field: it is easier to manufacture through Laser-based additive manufacturing technology and mechanically superior compared to pure copper, and it ensures values of thermal conductivity high enough to be considered a valid substitute for pure copper in many applications.The investigation on CuCrZr alloy was carried out in order to examine the influence of Direct Age Hardening (DAH) treatments on physical and mechanical properties. Laser Powder Bed Fusion technology was used to produce samples with CuCrZr alloy. The additive manufacturing process involved a machine provided with a 370 W IR laser and a preliminary process optimization was carried out to find the printing parameters that assured the highest density (99.15 %), which confirmed the processability of CuCrZr alloy also with low IR laser power. Then, three different DAH treatments were tested and the performance of DAHed material was compared to that of the alloy in as-built conditions. Precipitation phenomena were investigated with DSC analyses, revealing the effectiveness of the treatment already after 1 h. A deep microstructural investigation revealed a fine cellular structure formed during solidification and the presence of nanometric precipitates starting from the as-built condition. The presence of microstructural defects was also investigated. Mechanical performance and thermal conductivity were tested, too: the as-built samples showed limited properties, while very promising results for the use of additively manufactured CuCrZr components have been obtained after the DAHs. The ultimate tensile strength (UTS) and yield strength (YS) doubled the as-built values after 1 h treatment at 550 °C. The thermal conductivity reached three times the initial condition (from 100 W/mK to 300 W/mK).

Effect of remelting strategy on forming mechanism of selective laser melted AlSi10Mg

Selective laser melting (SLM) technology is widely used in various fields for manufacturing high-precision and complex parts. However, SLMed parts still exhibit some microstructural defects. The remelting strategy provides a new approach for defect elimination in SLM process, named as selective laser remelting (SLRM). In this study, the effects of remelting strategy on the melt pool were revealed through a finite element model. The porosity, microstructure, surface roughness, microhardness and tensile behavior of the specimens were also evaluated. The links between the formation mechanism of the melt pool and various experimental results were explored. The simulation results showed that the SLRMed melt pool had a significantly lower temperature and a shorter liquid phase time. The experimental results demonstrated that the remelting strategy effectively reduced the porosity, improved the density of the specimens, and provided a finer microstructure. The remelting strategy effectively reduced the surface roughness of the top surface of the specimens, while slightly adversely affecting the surface roughness of the side surface. Additionally, the microhardness and tensile properties of the specimens increased correspondingly due to the finer microstructure formed inside the SLRMed melt pool. These findings contribute to a better understanding and application of the remelting strategy for producing high-quality parts.

Utilization of Copper–Molybdenum Tailings to Enhance the Compressive Strength of Alkali-Activated Slag-Fly Ash System

Utilizing a variety of solid wastes to prepare alkali-activated cementitious materials is one of the principal trends in the development of cementitious materials. Commonly used alkali activation precursors such as granulated blast furnace slag (GBFS) and fly ash (FA) will be less available due to resource pressures. Supply limitation is an important reason to research alternative precursors. To realize the high value-added utilization of copper–molybdenum tailings (CMTs), this study adopted the modified sodium silicate solution as an alkaline activator to activate GBFS-FA-CMTs cementitious system to prepare alkali-activated cementitious materials. The influence of CMTs content on the compressive strength of GBFS-FA-CMTs cementitious system was analyzed, and the mechanism of GBFS-FA-CMTs cementitious system was also analyzed through hydration product types, physical phase composition, and microscopic morphology. The results indicated that a paste with the incorporation of CMTs, S50F30C20 (50% GBFS, 30% FA, 20% CMTs), achieved the highest compressive strength of 79.14 MPa, which was due to the filling effect of the CMTs and the degree of participation in the reaction. Pastes with different contents of CMTs, while maintaining a constant CBFS content, exhibited similar strength development. Excessive amounts of CMTs could result in reduced compressive strength. Microstructural analysis revealed that the hydration products were structurally altered by the addition of CMTs. In addition to ettringite, quartz, C(-N)-S-H gel, and calcite, gaylussite was also formed; moreover, the mass of chemically bound water increased, and the microstructure of reaction products became denser. An excess of CMTs may restrict the growth of the hydration gel, leading to more microstructural defects. The study suggests that CMTs could enhance the compressive strength of hardened paste within an alkali-activated slag-fly ash system, possibly due to a filling effect and participation in the chemical reaction. This research confirms the feasibility of using CMTs in alkali-activated cementitious materials.