Investigation of the influence of diverse reinforcements in aluminum-copper metal matrix composites through direct ink writing

ABSTRACT

Recent years have observed a significant increase in interest in the development of multi-metallic materials with reinforcing with reinforcement materials in alloys for advanced engineering applications. In this study, titanium (Ti), silicon carbide (SiC) graphite (Gr) and boron carbide (B₄C) were added at reinforcement percentages of 5% and 10% to develop aluminium-copper (Al–Cu) hybrid composites utilizing the Direct Ink Writing (DIW) method. Initially, to create printable inks with the required flow characteristics, the metallic and reinforcing powders were combined with a Pluronic F-127 binder and printed using printer. Further, to achieve densification and strong metallurgical bonding, the printed green parts were thermally post-processed. subsequently, the microstructural and mechanical characteristics of the final part were examined by a methodical characterization process, namely, X-ray diffraction (XRD), Vickers microhardness testing, optical microscopy and scanning electron microscopy (SEM). Moreover, the testing outcomes showed that the reinforced composites had significantly more refined grains, as compared to the base alloy. Then, EDS examination revealed no oxygen contamination, SEM analysis verified the homogeneous distribution of reinforcement particles throughout the matrix with enhanced interfacial bonding. From XRD studies a number of intermetallic phases, including Al₉Cu_11.5, AlCu, Al₁Cu₃, Al₁Cu₂Ti₁, Al_0.5Cu₁Ti_0.5, Al₃Cu₂, Al₂Cu_3.4, Al_35.472Cu_47.792 and Al₄Cu₉, were formed. In addition to its improved interfacial properties and refined grains, specimen S3 had the greatest hardness value of 759.9 HV of all the manufactured samples.

Keywords:
Direct ink writing; Metal matrix composites; Al–Cu alloy; Reinforcement; Mechanical properties; Multi-material AM

1. INTRODUCTION

Due to the remarkable strength, stiffness, and wear resistance, the use of metal matrix composites (MMCs) is attaining significant attention, in contrast to monolithic metals. The structural and functional effectiveness will be enhanced considerably by integrating ceramic and metallic reinforcements in a ductile metal matrix [¹]. To attain precise control over gradient structures and reinforcement distribution will be difficult with the help of conventional fabrication processes, including spark plasma sintering, stir casting, and powder metallurgy [²]. Complex geometries and multi-material systems with customized local compositions may now be fabricated because of the development of additive manufacturing (AM), especially direct ink writing (DIW) [³].

The controlled deposition of viscous inks that incorporate binders and metal fragments was enabled using an extrusion-based method, namely DIW. To print multiple material compositions within a single structure, attaining multi-material interfaces or functional gradients was possible with the printer’s flexibility [⁴, ⁵, ⁶]. However, there remain challenges with producing printable inks with optimum rheological characteristics, distributing reinforcements uniformly, and guaranteeing enough densification through sintering [⁷, ⁸, ⁹]. Current research suggests that active mixers can effectively homogenize multi-metallic materials in 3D printers [¹⁰].

The recent researchers are describing that the homogeneous mixing of multi-metallic materials is made possible with the use of active mixers incorporated 3D printer are as follows. Ober et al. [⁸] depict that active mixers are essential for ensuring that complex fluids are homogeneously mixed at microscale levels, overcoming limited diffusion. Ortega et al. [⁹] manifest that the active micromixers effective mix non-Newtonian inks, facilitating multi-material printing and precise gradients. The flame speed increased with improved homogeneity at higher mixing speeds, but once the material was thoroughly blended, it stagnated above 750 rpm. Anbarasan et al. [¹⁰] utilized an active mixer to fabricate a multi-material aluminium-copper (Al–Cu) alloy and optimized the corresponding post-processing parameters. This study shows that an active mixier is integrated with a 3D printer allows Cu particles to be uniformly distributed throughout the Al matrix. Further, the researchers have attempted to fabricate Al–Cu alloy via DIW with the help of active mixer methods and with other methods are as follows. ANBARASAN et al. [¹¹] developed a multi-material Al–Cu alloy with different composition and discovered that when post-processed at 700 C, the alloy with 40% Cu in Al showed the maximum hardness. DHARMADURAI et al. [¹²] examined the use of DIW as well as active mixing to fabricate Al–Cu multi-material components. For high-performance AM applications, the study demonstrated that optimal heat treatment significantly enhanced microstructure, decreased porosity, improved phase formation and increased mechanical performance. RAJASEKHAR et al. [¹³] reported that adding Cu to Al by powder metallurgy enhances the formation of intermetallic phases, such as Al₂Cu, which results in an approximate increase in the material’s overall hardness. ABDOLLAH-ZADEH et al. [¹⁴] studied about the AA1060-Pure Cu lap interface formed via friction stir welding, reported the development of AlCu, Al2Cu and Al4Cu3 intermetallic phases, highlighting significant metallurgical alteration. LIU et al. [¹⁵] manifest that formation of Al2Cu, Al0.939Cu0.987, Al₉Cu_11.5, and Al₄Cu₉ through the study of the Al–Cu structures made via solid-state diffusion bonding, resulting in increased mechanical characteristics.

Furthermore, the following are the contemporary researchers that have attempted to add various elements to Al–Cu alloys. MOSKVICHEV et al. [¹⁶] studied Cu–Al–Mn alloys with shape memory properties via electron beam AM and found microhardness values of 2.0 - 2.75 GPa and friction coefficients of 0.1 – 0.175. The study also showed that the right amount of heat input made it possible to make alloys that were reliable and parts that were free of defects. GOHAR et al. [¹⁷] examined Cu–10%Al–4%Ni alloys processed by sintering and cold compaction with different Ag additions. This study describes that, because of their finer microstructures, water-quenched samples displayed the most significant properties, attaining up to 241 HV hardness and 670 MPa compressive strength. KARTHIKEYAN et al. [¹⁸] studied the powder metallurgy of Al–Cu–Si composites and noticed that increased Cu enhanced sintered part density. Further, the higher Si levels greatly enhanced strength, and adding Si and Cu improved hardness and compression strength, which was further improved by reducing porosity. GHIAS et al. [¹⁹] observed fine equiaxed grains along with significant roles of diffusion and recrystallization in their study of friction welding of low-carbon steel, stainless steel, and Al–Cu. This study also reveals that Al–Cu joints had very low ductility (0.5–1%), whereas surface roughness impacted friction behavior. From the above literature arena, it is clear that the usage of active mixers can homogenize the multi-material in the printed part, and also it depicts that the addition of reinforcement in the Al–Cu alloy might increase the strength and form the respective intermetallic components. The Practical application for the Al–Cu composites are bushings, guide rails, wear plates, lightweight brackets, tooling fixtures, dies, heat sinks, electronic packaging components, sliding elements and other high-performance engineering applications.

According to the previous research inference, it is valuable to direct more effort toward exploring the addition of reinforcements to manufacture high-performance Al–Cu alloys through DIW. The foremost objective of this research is to investigate the influence of reinforcing material type and its concentration on the mechanical behavior, densification, and microstructure of MMCs developed using DIW. The study includes information for developing Al–Cu alloys with various reinforcements to improve properties that fulfill specific application needs.

2. MATERIALS AND METHODS

The process for fabricating Al–Cu hybrid composites using DIW is shown in Figure 1. It includes material selection, ink formulation, printing, post-processing and characterisation.

Figure 1
Process flowchart.

2.1. Raw materials

Pure powders of Cu and Al, each with a particle size less than 200 mesh, were purchased from Nice Chemicals (P) Ltd. in India. The polymeric binder Pluronic F-127, which is necessary for the formulation of ink and its printability, was acquired from Sigma-Aldrich in the United States. The selection of reinforcement materials, which had particle sizes less than 200 mesh, was obtained from Otto Chemie Pvt. Ltd. and comprised titanium (Ti), silicon carbide (SiC), graphite (Gr), and boron carbide (B₄C). The uniform dispersion, reliable sintering behavior, and consistent mechanical characteristics in the fabricated metal matrix composites were guaranteed by the high-purity raw materials. To achieve the ideal rheological and structural properties for direct ink writing (DIW) of multi-reinforced Al–Cu composites, each material has been selected carefully.

2.2. Material composition variation

A predetermined metal matrix composition of 60% Al and 40% Cu was employed in this study to fabricate eight different Al–Cu-based composite formulations, based on the characteristics attained by former research. The four different reinforced materials, namely boron carbide (B₄C), graphite (Gr), silicon carbide (SiC), and titanium (Ti), are used for ink formation; each reinforcement is added at 5% and 10% volumetric concentrations. Samples S1 to S8 are recognized through their chemical compositions: S1 and S2 possessed 5% and 10% Ti, respectively; S3 and S4 included 5% and 10% SiC; S5 and S6 contained 5% and 10% Gr; and S7 and S8 had 5% and 10% B₄C as reinforcement.

2.3. Direct ink writing

To fabricate the Al–Cu alloy composites with various reinforcements was carried out using the DIW approach, comprising three fundamental steps: ink formulation, printing, and post-processing. During the ink formation process, Al, Cu, and the respective reinforcement powders were mixed at preset ratios with the polymeric binder Pluronic F-127 to form ideal rheological characteristics. In order to homogenize the mixture, a mechanical stirrer (Remi RQ-127/D, India) was employed; 180 seconds at 1200 rpm was preferred. These characteristics provided a steady ink viscosity that was suitable for extrusion and uniform particle dispersion. A specially made 3D printer (Fabforge DS1, India) with an active mixing system that prevents particle sedimentation and preserves ink consistency during deposition was used for the printing process. In order to ensure uniformity, the printing parameters were selected around 40 psi for all compositions, 5 mm/s as printing speed, 60 rpm for the auger speed, 2 mm for nozzle diameter, and 2 mm for layer thickness. The green parts, or printed structures, were dimensionally stable and prepared for further heat treatment. During the post-processing stage, sintering, debinding, and drying were performed. The printed samples were dried for 24 hours to eliminate moisture and solvent. To effectively remove the binder, thermal debinding was subsequently carried out in a vacuum hot press (VB Ceramics, India) at a pressure of 5 bar, a peak temperature of 350°C, a heating rate of 3°C/min, and a holding time of 60 minutes. Lastly, to improve densification and strong metallurgical bonding, sintering was carried out at 700°C under 20 bar of pressure with a heating rate of 5°C/min and a dwell period of 60 minutes. The 3D printing setup, the printed green component, and the final processed part manufactured after manufacturing are all illustrated in Figure 2. The fabrication of multi-material Al–Cu composites with unique mechanical and functional characteristics suitable for cutting-edge engineering applications was made possible by the precise control over composition, microstructure, and density provided by this DIW-based technique.

Figure 2
(a) 3D printer, (b) green part and (c) final part.

2.4. Characterization

The Al–Cu alloy composites with different reinforcement ratios were characterized by mechanical and microstructural investigations. A rotational rheometer was employed to assess the formulated inks shear-thinning behaviour and other rheological characteristics that are essential to DIW. To guarantee precision and consistency, the mechanical properties of the part, hardness, were measured using a Vickers microhardness tester with a 200-gf force applied for 15 seconds. For microstructural analysis, optical microscopy (OM) at 100X magnification was carried out to identify grain structure and surface characteristics. Further, scanning electron microscopy (SEM) was used to examine in detail to confess particle dispersion, interfacial bonding, and porosity. Moreover, an energy-dispersive spectroscopy (EDS) study was carried out to map elemental distribution within the MMC matrix. Furthermore, X-ray diffraction (XRD) throughout a 2θ range of 10°–90° was characterized to analyze crystalline phases and phase growth.

3. RESULT AND DISCUSSION

3.1. Rheology analysis

As the formed inks were evaluated over a range of shear rates is shown in Figure 3, The rheological behaviour showed a noticeable shear-thinning (pseudoplastic) characteristic, where viscosity gradually reduced as shear rate increased [²⁰, ²¹]. This behaviour is particularly beneficial for DIW applications because it allows for quick viscosity recovery after deposition and smooth ink extrusion through the printing nozzle under shear stress, retaining the integrity of the printed structure. All formulations demonstrated a noticeable reduction in viscosity when powder particles were added, revealing alterations in the internal network and particle-binder interactions. Particle packing, interparticle friction and alignment during flow were also impacted by variations in particle size and morphology, that exhibited significant effects on printability and rheological performance.

Figure 3
Formulated ink rheology outcomes (a) Ti-reinforced ink, (b) SiC-reinforced ink, (c) Gr-reinforced ink and (d) B4C-reinforced ink.

3.2. Microstructural observations

3.2.1. Optical microscope

The different phase distributions and morphologies were examined in the microstructures of Al–Cu composites with different reinforcements. The Sample S3 demonstrated a fine granule that possesses apt composition with an appropriate sintering process. This study confesses that the increased grain refinement results through diverse reinforcement content. The outcome of the optical microscope was displayed in Figure 4.

Figure 4
Optical microscope analysis.

The microstructure of the sample S1 shows refined and heterogeneous grains, where the Ti acts as a grain refiner. Optical microscopy reveals angular to subrounded grains with darker Ti-induced nucleation sites and reflective phases rich in Al and Cu. The grain coarsening and improved boundary definition with the heterogeneous nucleation were carried out by Ti inclusion. The microstructure of the sample S2 displays a heterogeneous grain distribution, revealing a multiphase structure with a refined configuration due to Ti addition. This also confesses a combination of rounded and angular grains. The ceramic reinforcement in sample S3 resulted in a heterogeneous grain structure that exhibited both refinement and improved dispersion. Moreover, this study also depicts that angular and sub-rounded grain structures are present in S3. The microstructure of the sample S4 exhibits homogeneous SiC dispersion and refined angular grains. The interconnecting grains with light-reflective Al- and Cu-rich phases are visible under optical microscope study. The microstructure of the sample S5 possesses a heterogeneous grain structure with improved interfacial contrast and dispersion. Further, this study reveals that the grain is angular and subrounded in shape. The refined, angular grains are observed in the sample S6 microstructure, and also uniformly distributed Gr inclusions were noted. This study discloses that the Gr inclusion stabilizes grain boundaries and reduces coarsening by acting as a solid lubricant and stress distributor. The microstructure sample S7 depicts refined angular grains with uniformly distributed B₄C particles. Further, the microstructure of the sample S8 reveals highly refined and angular grains, which improve thermal stability and mechanical strength. By this research, the B₄C particle inclusion in the Al–Cu alloy facilitates grain refinement, enhanced bonding, and heterogeneous nucleation.

By this optical microscopy study, each sample possesses distinct grain structures, revealing that grain formation depends on both the type and amount of the reinforcing material along with post-processing parameters. Moreover, the interlinked strengthening networks of Al–Cu composites have identified enhanced mechanical properties like strength and toughness. These composites, which possess interlinked strengthening networks, enhance the material’s flexibility for demanding structural applications by enabling optimal load transfer.

3.2.2 SEM analysis

The SEM-EDS analysis demonstrated strong interparticle bonding, and a major reduction in porosity was imparted by the use of an active mixer incorporated into the 3D printer. Further, the SEM image demonstrates that diffusion processes and particle rearrangement reduce the majority of voids. Furthermore, enhancing the sintering parameter could improve density and strengthen the material’s overall structural integrity.

The addition of Ti reinforcement to the Al–Cu matrix was observed in figure 5. The Ti particles are uniformly distributed throughout the alloys S1 and S2, as shown in figures 5(a) and 5(c). Further, the EDX images in figures 5(b) and 5(d) confirm the successful addition of reinforcement by ensuring the presence of Al, Cu, and Ti elements. Moreover, the spectra indicate that there was no oxide formation, indicating that the alloy’s chemical integrity was preserved during processing. The inclusion of SiC reinforcement in the Al–Cu matrix is illustrated in figure 6. The SEM images show that the SiC particles are evenly distributed throughout the alloy, as shown in figures 6(a) and 6(c). Further, the corresponding EDX spectra shown in figures 6(b) and 6(d) show that Al, Cu, and SiC are present without any indication of oxide formation. The significant enhanced mechanical property in the addition of SiC depicts the effectiveness of reinforcement inclusion by increasing strength and improving overall performance. Figure 7 demonstrates the incorporation of Gr reinforcement into the Al–Cu matrix. The SEM image confesses that Gr powder was equally dispersed throughout the alloy shown in figures 7(a) and 7(c). Further, the absence of oxide formation and also the confirmation of the existence of Al, Cu, and Gr elements confirmed by EDX studies were displayed in figures 7(b) and 7(d). Figure 8 displays the integration of B’C reinforcement into the Al–Cu matrix. Further, B₄C particles were evenly distributed throughout the alloy, as seen by the micrographs in figures 8(a) and 8(c). Then the associated EDX studies demonstrate an absence of oxide formation, while validating the existence of Al, Cu, and B₄C particles, as shown in figures 8(b) and 8(d).

Figure 5
Outcomes of SEM with EDX of Ti reinforcement: (a) sample S1 SEM image, (b) sample S1 EDS outcome, (c) sample S2 SEM image, and (d) sample S2 EDS analysis.

Figure 6
Outcomes of SEM with EDX of SiC reinforcement: (a) sample S3 SEM image, (b) sample S3 EDS outcome, (c) sample S4 SEM image, and (d) sample S4 EDS analysis.

Figure 7
Outcomes of SEM with EDX of Gr reinforcement: (a) sample S5 SEM image, (b) sample S5 EDS outcome, (c) sample S6 SEM image, and (d) sample S6 EDS analysis.

Figure 8
Outcomes of SEM with EDX of B4C reinforcement: (a) sample S7 SEM image, (b) sample S7 EDS outcome, (c) sample S8 SEM image, and (d) sample S8 EDS analysis.

According to SEM analysis, all samples exhibit a homogeneous distribution of reinforcement embedded within the Al–Cu matrix. A 3D printer with an integrated active mixing system is used to fabricate the part for the purpose of ensuring this homogeneous distribution. Additionally, the micrographs show an absence of oxide formation, confirming that the alloy’s chemical integrity remained intact during processing. Due to the post-processing process being carried out in a vacuum, the formation of oxides is negligible. It is anticipated that the oxide-free microstructure and thus even distribution of reinforcement would improve mechanical properties like strength and stability. The results obtained reveal the degree to which the processing technique performs for producing composites with identical microstructural integrity as well as the alloy composition.

3.3. Phase analysis

As shown in figure 9, eight samples representing the final parts performed XRD analysis. All three samples show distinct diffraction peaks in the information, indicating that the final parts possess a discrete crystalline structure. The predominant diffraction peaks of sample S1 correspond to ICSD patterns of 98–007-7000, 98–002-3841 and 98-010-3949, that demonstrate the existence of Al₉Cu_11.5, AlCu and AlCu₃ intermetallic crystals, are in agreement with this pattern. The dominant diffraction pattern in sample S2 consistent with ICSD patterns 98-007-7000, 98-002-3841, 98-010-3949, 98-006-5741 and 98-006-5742, demonstrating the presence of intermetallic crystals of Al₉Cu_11.5, AlCu, AlCu3, Al₁Cu₂Ti₁ and Al_0.5Cu₁Ti_0.5. The intermetallic crystals Al₉Cu_11.5 and AlCu can be observed in ICSD patterns 98-007-7000 and 98-009-2198, which correspond to sample S3 pattern. The pattern of sample S4 correlates with the ICSD patterns of 98-007-7000, 98-009-2198, 98-010-3949, 98-006-5690 and 98-006-5689, demonstrating the possible presence of intermetallic crystals of Al₉Cu_11.5, AlCu, Al₁Cu₃, Al₃Cu₂ and Al₂Cu_3.4. The diffraction pattern of sample S5 matches ICSD patterns of 98–007-7109 and 98-002-3841, which depict the presence of Al_35.472Cu_47.792 and AlCu intermetallic crystals. The ICSD patterns of 98-007-7109 and 98-002-3841, demonstrating an indication of Al_35.472Cu_47.792 and AlCu intermetallic crystals, correspond with sample S6 pattern. The dominant diffraction peaks of sample S7 indicate the presence of Al_35.472Cu_47.792 and AlCu intermetallic crystals, that are consistent with ICSD patterns of 98-007-7109 and 98-002-3841.

Figure 9
Phase analysis.

XRD examination demonstrates that the addition of different reinforcements to the Al–Cu alloy resulting in the development of numerous intermetallic phases, including Al₉Cu_11.5, AlCu, Al₁Cu₃, Al₁Cu₂Ti₁, Al_0.5Cu₁Ti_0.5, Al₃Cu₂, Al₂Cu_3.4, Al_35.472Cu_47.792 and Al₄Cu₉. These phases developed effectively as a result of meticulously controlled sintering conditions and reinforcement additions, which jointly affected phase stability and nucleation behaviour. While sintering parameters like temperature and applied pressure controlled the stability and transition of these phases, reinforcements served as nucleation sites, encouraging the development of certain intermetallic compounds. Alloying materials and processing variables performed in concert to create a complex microstructure with a customized crystalline architecture. There is an apparent relationship between improved mechanical performance and the presence of these intermetallic. As a result of the phases’ strengthening impact, hardness values increased considerably. These substances enhance the ability to support loads, withstand deformation, and support the general integrity of the material. Considering this, the reinforced Al–Cu alloys are more durable than conventional - based alloys. The primary finding is that the main process behind property increase in Al–Cu alloys is reinforcement-driven phase formation. Alloys with increased hardness and stability may be developed through optimizing the kind of reinforcement and sintering conditions, making them suitable for demanding industrial and technical applications.

3.4. Density

Depending on the type and amount of reinforcement added to the matrix, the density of the produced Al–Cu hybrid composites was calculated to range from 4.12 to 4.56 g/cm³. Density is a crucial characteristic that affects composite materials’ weight, structural effectiveness, and service performance, especially in applications the inquiry for a high strength-to-weight ratio. The Ti-reinforced composites showed in Figure 10, the greatest density values among the examined samples; S1 and S2 recorded densities of 4.48 g/cm³ and 4.56 g/cm³, respectively. The significantly increased density of titanium particles and their successful incorporation into the Al–Cu matrix is responsible for this increase.

Figure 10
Density outcomes.

On the other hand, graphite-reinforced composites had the lowest densities; S5 and S6 had densities of 4.24 and 4.12 g/cm³, respectively. The major cause of the density decrease is graphite’s naturally low density, which helps reduce weight without sacrificing sufficient mechanical performance. In contrast, the composites supplemented with SiC and B4C showed intermediate density values, ranging from 4.15 to 4.36 g/cm³. The decreased density of these reinforcements as compared to the Al–Cu matrix is linked to the slight reduction in density that is seen with increasing concentrations of SiC, Gr and B4C.

Overall, the findings show that by methodically selecting and concentrating reinforcement, the density of Al–Cu hybrid composite materials may be adjusted. Because of this versatility, lightweight materials with increased performance characteristics may be developed, which makes them desirable for advanced engineering applications such as thermal management, automotive and aerospace, where both better performance and weight reduction are desired.

3.5. Hardness analysis

The mechanical characteristics of Al–Cu-based composites on the influence of distinct reinforcements have been determined by hardness analyses and are shown in figure 11. The hardness values that were measured were as follows: 751.7 HV (S1), 545.2 HV (S2), 759.9 HV (S3), 602.2 HV (S4), 732.3 HV (S5), 707.8 HV (S6), 343.9 HV (S7), and 571.4 HV (S8). The sample S3 demonstrated the maximum hardness of 759.9 HV because of efficient interfacial bonding and grain refinement from SiC particles, a 15.8% betterment over the reference hardness of 656 HV [¹¹]. The sample S1 measures to be 751.7 HV, possessing dislocation pinning and grain boundary resistance due to the strengthening impact of 5% Ti, and was 14.6% greater than 656 HV. Moreover, minimal plastic deformation and better bonding in graphite-reinforced samples S5 and S6 display increases of 7.9% and 11.6%, respectively. Furthermore, particle clustering and poor interfacial cohesion lead to decreases of up to 16.9% in hardness for samples S2 (545.2 HV) and S7 (343.9 HV), along with small reductions in hardness for samples S4 (602.2 HV) and S8 (571.4 HV).

Figure 11
Analysis of hardness value.

Analyzing the Al–Cu-based composite shows significant variations in hardness that focus on the influence of both reinforcement type and quantity. The substantial strengthening caused by 5% Ti indicates that the hardness of sample S1 is 27.5% greater than that of sample S2. Further, by decreasing Ti concentration, the grain boundary strengthening and effective dislocation pinning are observed. Then the improved hardness through superior interfacial bonding and grain refinement was demonstrated in 5% SiC, showing S3 exceeds S4 by 20.8%. Furthermore, the sample S5 is 3.3% more durable than S6 in Gr-reinforced samples, indicating a minimal variation and implying that the hardness improvement from higher graphite content is confined. Moreover, the S8 is 65.9% harder than the S7, indicating that a larger B₄C content significantly strengthens the composite. This shows that the most noticeable difference is seen in samples reinforced with B₄C. By the above consideration, this analysis confesses that the sample S3 with 5% SiC possesses remarkable hardness, wear resistance, and structural reliability appropriate for demanding engineering applications.

Hardness analysis reveals that the material composition of the alloy is crucial in influencing its mechanical properties, along with homogenous mixing. Even though the SEM image confirms a uniform dispersion of reinforcement in all samples, hardness analysis indicates that the intrinsic material contents of the alloy are a significant factor determining its performance.

4. CONCLUSION

This research focuses on utilizing DIW together with an active mixer to fabricate an Al–Cu multi-metallic part with diverse reinforcements. The dense Al–Cu alloys, which exhibit significant hardness, can be effectively developed using the DIW method in conjunction with the active mixing system, thereby enhancing the efficiency of the printing process. The research’s major findings are summarized as follows.

• The improved grain refinement that was caused by the variable reinforcement content provided an indication of the influence of reinforcement on microstructure.

• The SEM investigation reveals a uniform distribution of the corresponding reinforcement particles within the Al–Cu alloy matrix. The identification of the required reinforcement in the Al–Cu alloy and an absence of oxygen is further confirmed by the EDS analysis.

• XRD analysis shows that adding different reinforcements to the Al–Cu alloy makes it easier for many intermetallic phases to form, such as Al₉Cu_11.5, AlCu, Al₁Cu₃, Al₁Cu₂Ti₁, Al_0.5Cu₁Ti_0.5, Al₃Cu₂, Al₂Cu_3.4, Al_35.472Cu_47.792, and Al₄Cu₉.

• S3 achieved a maximum hardness of 759.9 HV through excellent interfacial bonding and grain refinement.

The present research demonstrates a feasible and cost-effective DIW approach for fabricating strong, lightweight parts used in electronics, automotive, and aerospace applications. To maximize performance and enhance the technique’s potential, it emphasizes improved hardness and dependability while promoting additional research on novel materials and interfacial bonding.

5. DATA AVAILABILITY

All data analyzed during this study are included in this published article.

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Publication Dates

• Publication in this collection
  10 Aug 2026
• Date of issue
  2026

History

• Received
  21 Jan 2026
• Accepted
  08 July 2026