Search Results (62)

In this work, a non-standardized hypereutectic aluminum–silicon alloy AlSi21Cu5MgCr intended for the automotive industry is presented. The modification of the alloy is performed with the conventional modifier phosphorus in an amount of 0.04 wt%. The applied metallurgical treatment is the basis for the obtained modified structure. It has been established that after conducting the T6 heat treatment, the free silicon crystals are reduced to 26.9 µm, and the eutectic silicon crystals are spherical in shape and have dimensions not exceeding 8 µm. The macrohardness of the studied alloy is 168.5HV_10/10, a value significantly higher than that required for this type of alloy, which is in the range of 95 ÷ 137 HV (90 ÷ 130 HB). The microhardness of the α-phase in the composition of the eutectic is 154 µHV_50/10, which indicates that after quenching a saturated solid solution was fixed, and during the artificial aging process secondary strengthening phases were formed and separated. A CrAlN hard coating was deposited on the alloy surface. The mechanical properties of the coating were characterized by a hardness of 14 GPa, whereas the AlSi21Cu5MgCr substrate had a hardness of 2 GPa. The results showed considerable improvement of the hardness of the new alloy and well-tuned elastic–plastic properties. The obtained adhesive properties are compatible with this class of materials. The composition of the CrAlN hard coating is homogeneously distributed on the alloy surface and the morphology is improved. The investigations showed that CrAlN hard coatings could successfully be applied for the modification of the surface of AlSIMgCu alloys. Full article

To address the demand for lightweight, high-performance Al-Si-Mg alloys in aerospace and automotive industries, this work proposes a novel synergistic strengthening strategy by combining rare-earth Y microalloying and in situ synthesized ZrB₂ nanoparticles to construct a hybrid reinforcement architecture. The effects of Y-ZrB₂ additions on the microstructure, crystallographic orientation evolution, and mechanical properties of Al-Si-Mg alloys were systematically investigated via XRD, SEM, EBSD, and tensile/hardness tests. Results show that compared with the base alloy and single-modified alloys, the co-addition of Y and ZrB₂ simultaneously enhances mechanical properties and optimizes grain structure. The optimal comprehensive performance is achieved at 0.3 wt.% Y + 2 wt.% ZrB₂ after T6 heat treatment, with ultimate tensile strength of 332.87 MPa, yield strength of 271.35 MPa, elongation of 16.24%, and Vickers hardness of 153.9 HV. Phase analysis and SEM-EDS confirm a synergistic coupling relationship between Y-rich phases and ZrB₂ nanoparticles. EBSD characterization reveals that Y-ZrB₂ modification has negligible effect on the morphology and crystallographic orientation stability of primary α-Al grains, but effectively regulates the lattice rotation, texture redistribution, and growth behavior of eutectic Si. At the optimal composition, the fraction of high-angle grain boundaries (HAGBs) reaches a maximum of 34.3%. Furthermore, the synergistic effect significantly increases the geometrically necessary dislocation (GND) density and reduces the Schmid factor of the dominant {111}⟨110⟩ slip system, thus enhancing dislocation strengthening and plastic deformation resistance. This work clarifies the intrinsic strength-ductility synergy mechanism of Y-ZrB₂ co-modified Al-Si-Mg alloys, paving a new pathway for the development of advanced lightweight aluminum alloys. Full article

Biodegradable poly(lactide)/poly(ε-caprolactone) (PLA/PCL) systems functionalized with TiO₂-SiO₂ were synthesized via in situ ring-opening polymerization of a eutectic L-lactide/ε-caprolactone system. This work introduces a TiO₂-SiO₂ composite with a dual function, acting as a catalytic initiator that governs polymerization and microstructure, while simultaneously serving as a reinforcing and photocatalytic phase. The system exhibits high polymerization efficiency, reaching conversions up to 99% with low filler loadings (0.1–1.0 wt%). Structural analyses confirm polymer formation and reveal modifications in ester groups associated with coordination-driven mechanisms. Notably, the presence of TiO₂-SiO₂ promotes increased PLA tacticity, directly influencing mechanical performance. The resulting materials show enhanced tensile strength (~250,000 Pa) and Young’s modulus (1.5–2.0 MPa) compared to conventional systems. In addition, excellent photocatalytic activity was achieved, with up to 99.7% degradation of methyl orange. These findings demonstrate a synergistic strategy to simultaneously control polymer structure and functionality, positioning PLA/PCL–TiO₂-SiO₂ systems as promising multifunctional materials for environmental applications. Full article

Cooling curve analysis enables accurate determination of aluminum alloy solidification parameters while capturing important non-equilibrium phenomena that are difficult to resolve using thermodynamic models alone. Modern casting simulation tools such as MAGMASOFT and ProCAST provide advanced capabilities, including user-defined material databases and microstructure models, but their predictive accuracy depends strongly on the quality of alloy-specific input data. In particular, the effects of trace element variations and chemical modification treatments, such as strontium-induced depression of the Al–Si eutectic temperature, are not always quantitatively represented in generic databases. This study demonstrates that thermal analysis provides experimentally based solidification data under controlled cooling conditions representative of foundry practice. Cooling curve analysis directly records undercooling, recalescence, and modification-induced temperature shifts, including eutectic temperature changes of ~10 °C after strontium treatment, which significantly influence solidification kinetics and defect formation. A short industrial thermal analysis test enables the extraction of key parameters, including liquidus, eutectic, coherency, rigidity, and solidus temperatures; fraction-solid evolution; and latent heat release. When integrated into casting simulation databases, these experimentally derived parameters support improved modeling of feeding behavior, shrinkage porosity risk, hot tearing tendency, and microstructure development. The proposed approach positions cooling curve analysis as a practical complementary tool for calibrating and enhancing simulation input data under real alloy and process conditions. Full article

Hypoeutectic aluminum–silicon casting alloys in their unmodified state have a coarse-grained eutectic (α + β), which results in poor mechanical properties and brittleness. Microstructure refinement and improved mechanical properties are possible, among other things, by introducing various elements and chemical compounds. The literature presents numerous studies on the modification of hypoeutectic silumins, but there are no results confirming the effectiveness of the interaction of a master alloy containing titanium and boron with its main component, which may be aluminum, aluminum with silicon, or aluminum with silicon and magnesium. This paper presents the results of microstructure refinement using titanium or boron introduced into the Al, AlSi7, and AlSi7Mg master alloys. The introduction of titanium and boron into the aluminum-based master alloy resulted in microstructure refinement and improved mechanical properties. The results indicate that the most favorable results were obtained when titanium and boron were introduced into the AlSi7 master alloy. The addition of magnesium to the master alloy AlSi7 resulted in less effective microstructure refinement of the AlSi9 silumin, which resulted in lower mechanical properties than those obtained for the master alloy without Mg. Full article

The room-temperature and high-temperature microstructural characteristics and tensile properties of an Al-12Si-4Cu-2Ni-0.5Mg piston alloy modified with calcium (Ca; denoted as AC sample) or phosphorus (P; denoted as AP sample) under different heat treatment conditions were systematically analyzed. Under Ca modification, the second-phase network structure of the alloy was adjusted and strengthened by an Al-TCB master alloy. Eutectic silicon (Si) particles in the AC sample possessed a fibrous structure, whereas the AP sample contained elongated eutectic Si particles, and Ca modification was found to be a potential method for simultaneously enhancing the strength and plasticity of the alloy to a matching degree at high temperatures. The T6 treatment noticeably increased the density of nanoscale precipitates; however, it also disrupted the growth of the second-phase network structure. Micron and submicron C-TiB₂ and Al₄C₃ particles formed by the in-situ reaction of TCB particles acted as bridging phases within the second-phase network structure and enhanced the strength of the piston alloy. The ultimate tensile strength of the alloy at 350 °C increased from 74 to 101 MPa, representing a 36.5% enhancement. A comprehensive analysis revealed that Orowan strengthening was the main strengthening mechanism of the alloy at room temperature, whereas load transfer and network structure strengthening were the dominant strengthening mechanisms at high temperatures. Full article

Al-Si phase change materials are widely used in solar thermal power generation and industrial waste heat reclamation due to their high heat storage density, high phase transition temperature, and low cost. Hypoeutectic Al-7Si phase change thermal storage alloys with trace La additions were produced through smelting and casting to examine how La affects their microstructural characteristics and thermophysical performance. The findings show that La is adsorbed at the eutectic Si growth interface. Due to the difference in atomic radii, it alters the stacking sequence of Si atoms, generating numerous high-density staggered twins on the {111}Si planes of eutectic Si. La additions modify the morphology of eutectic Si, leading to a morphological transition from lamellar to short rods structures with reduced dimensions. The optimal eutectic Si modification is achieved with 0.06 wt.% La addition. The altered morphology and reduced size of the eutectic Si phase enhance the continuity of the α-Al matrix. This reduces the scattering of free electrons by eutectic Si, increases their mean free path, and ultimately improves the thermal conductivity of the alloy. With 0.06 wt.% La addition, the Al-7Si alloy achieved a peak thermal conductivity of 179.3 W·m⁻¹·K⁻¹, representing a 15.36% enhancement over the unmodified alloy. After 100 thermal cycles, the alloy maintained its phase transition temperature, but the modification effect of La diminished, as evidenced by increased formation of lamellar eutectic Si. Consequently, the latent heat of the Al-7Si-0.06 alloy decreased from 340.4 J/g to 328.6 J/g. Full article

The present study examines the structure, properties and use of complex-alloyed hypereutectic aluminium-silicon alloys, emphasising the control of the morphology of primary silicon via treatment with various modifiers as well as their effects on its shape and distribution. Furthermore, this study reviews the experimental work related to the simultaneous modification of primary and eutectic silicon, which leads to the conclusion that favourable results can be obtained by complex modification treatment involving first- and second-type modifiers. After being cast, the AlSi18Cu3CrMn and AlSi18Cu5Mg non-standardised piston alloys are subjected to T6 heat treatment intended to enhance their mechanical performance, harnessing the full potential of the alloying elements. A microstructural analysis of the shape and distribution of both primary and eutectic silicon crystals following heat treatment was employed to determine their microhardness. Full article

In this investigation, it was found that the co-addition of Er and B causes both the modification and refinement of the Al-7Si alloy. The B element mainly forms a small amount of the AlB2 phase within the alloy, which can be used as a nucleation site for grains during casting, so the addition of B can significantly reduce the grain size of the Al-7Si alloy. However, the number density of AlB2 phase is too low, so its effect on improving the eutectic Si size and reducing the secondary dendrite arm spacing (SDAS) is not significant. The addition of 0.1 wt% Er can form a large amount of Al3Er phase within the alloy, which mainly serves as a nucleation site for eutectic Si during casting, so the addition of Er can significantly reduce the SDAS, eutectic Si size and morphology of Al-7Si alloys. However, due to the existence of a certain degree of mismatch between the Al matrix and the Al3Er phase, the relative grain refinement effect of Al3Er is not significant. In addition to this, we also observe the enrichment of Er at eutectic Si, which suggests that Er can interact with Si and thus inhibit the growth of eutectic Si. Therefore, Er can modulate eutectic Si through the Al3Er phase and the enrichment of Er. The co-addition of Er and B to Al-7Si alloys has better refining and modification effects than the addition of Er or B alone, mainly due to the modification effect of the Er element and the refining effect of the AlB2 phase. Unlike the Er-containing alloys, where the Al3Er phase plays a modifying role, the modification of the co-addition Er and B alloys is mainly caused by the enrichment of Er within the alloy. Full article

This study presents an efficient method for detecting oxytetracycline, which is critical in environmental monitoring and food safety. A highly sensitive detection platform was developed by combining molecularly imprinted polymers (MIPs) with silica as a carrier, modified with deep eutectic solvents (DES), and a quartz crystal microbalance (QCM) sensor. The MIPs were specifically designed to target oxytetracycline hydrochloride, using SiO₂ as the carrier, DES as the functional monomer, N, N-methylenebisacrylamide as the crosslinker, and ammonium persulfate as the initiator. The MIPs exhibited an adsorption capacity of 27.23 mg/g for oxytetracycline hydrochloride. After modification of the MIPs onto a gold electrode surface, a QCM-based sensor platform was constructed. The sensor demonstrated an exceptionally low detection limit of 0.019 ng/mL for oxytetracycline and exhibited excellent sensitivity in tap water. Furthermore, the sensor maintained over 90% detection performance after two weeks of room-temperature storage, indicating its stability. This method provides a rapid, highly sensitive approach for oxytetracycline detection, with potential for future improvements and widespread application in antibiotic testing. Full article

This study investigates the impact of strontium (Sr) additions on the corrosion resistance of an LM6 (A413) aluminium alloy. By incorporating varying concentrations of Sr (0.01 wt.% and 0.05 wt.%), the morphological and corrosion behaviours of the alloy were analysed under different corrosive environments, including sulphuric acid, sodium hydroxide, and sodium chloride solutions. The results demonstrate that Sr modifications significantly enhance the alloy’s corrosion resistance, with the most substantial improvement observed at 0.05 wt.% Sr. The analysis revealed that the weight loss of the alloy in sulphuric acid decreased by 2.5% with 0.05 wt.% Sr after 10 days of immersion, due to the formation of a stable passive oxide layer. In sodium hydroxide, however, the weight loss was reduced by 5% with 0.05 wt.% Sr after 10 days, indicating aggressive uniform corrosion. In the 3.5% sodium chloride solution, the corrosion rates remain relatively low, and the 0.05 wt.% Sr alloy showed a decrease in corrosion product formation over time, suggesting enhanced resistance. Detailed surface analyses, including 3D profiling and morphology assessments, revealed that Sr additions refine the eutectic silicon phase, transforming it from a coarse to a more desirable fibrous or lamellar structure, thus improving the alloy’s overall performance. The innovative findings underscore the potential of Sr as an effective microstructural modifier for enhancing the durability and longevity of Al-Si alloys in corrosive environments. Full article

This study investigated the effect of adding La–Ce mixed rare earths and Sr on the microstructure and mechanical properties of AlSi10MnMg alloy. The experiment utilized different combinations of modifiers, including single La–Ce rare earths, single Sr, and the combined addition of La–Ce mixed rare earths and Sr. This study compared their effects on grain refinement, the modification of the α-Al phase and eutectic silicon phase, and tensile properties and hardness. The results showed that the combined modification of Sr and mixed rare earth elements significantly refined the grains, optimized the morphology of the α-Al phase and eutectic silicon phase, and improved the overall mechanical properties of the aluminum alloy. Under the combined modification, the addition of 0.02 wt.% Sr and 0.1 wt.% RE (La–Ce mixed rare earths) exhibited the most pronounced refining effect. The secondary dendrite arm spacing (SDAS) was reduced by 59.18%. The eutectic silicon phase transformed from coarse needle-like shapes to fine fibrous or granular forms, with an aspect ratio reduction of 69.39%. Meanwhile, the alloy’s tensile strength and hardness were significantly improved. The tensile strength increased to 240 MPa, achieving an increase of 23.08%; the yield strength increased to 111 MPa, achieving an increase of 18.09%; and the elongation reached 7.3%, achieving an increase of 73.81%. This indicates that the proper addition of Sr and mixed rare earths can significantly optimize the microstructure and enhance the mechanical properties of AlSi10MnMg alloy, providing an effective method for the preparation of high-performance heat-treatment-free aluminum alloys. Full article

This study investigates the impact of varying extrusion ratios on the microstructure and mechanical properties of AlSiCuFeMnYb alloy. Following hot extrusion, significant enhancements are observed in the microstructure of the cast rare earth aluminium alloy. Within the cross-sectional microstructure, the α-Al phase is reduced in size, and its dendritic morphology is eliminated. The morphology of the eutectic Si phase transitions from long strips to short rods, fine fibres, or granular forms. Similarly, the Fe-rich phase changes from a coarse skeletal and flat noodle shape to small strips and short skeletal forms resembling Chinese characters. The CuAl₂ phase evolves from large blocks to smaller blocks and granular forms, while the Yb (Ytterbium)-rich rare earth phase shifts from large blocks to smaller, more uniformly distributed blocks. In the longitudinal section, the structure aligns into strips along the extrusion direction, with the spacing between these strips decreasing as the extrusion ratio increases. At an extrusion ratio of 22.56, the alloy demonstrates superior mechanical properties with a tensile strength of 325.50 MPa, a yield strength of 254.44 MPa, a hardness of 143.90 HV, and an elongation of 15.47%. These represent improvements of 27.8%, 36.5%, 38.9%, and 236.4%, respectively, compared with the as-cast rare earth alloy. In addition, the fracture surface of the extruded rare earth alloy exhibits obvious ductile fracture characteristics. Additionally, the alloy undergoes dynamic recrystallisation and dislocation entanglement during hot extrusion. The emergence of a twinned Si phase and a dynamically precipitated nanoscale CuAl₂ phase are critical for enhancing deformation strengthening, modification strengthening, and dynamic precipitation strengthening of the extruded alloys. Full article

The high-temperature composite phase change materials (HCPCMs) were prepared from solid waste blast furnace slag (BFS) and NaCl-KCl binary eutectic salt to achieve efficient and cost-effective utilization. To ensure good chemical compatibility with chlorine salt, modifier fly ash (FA) was incorporated and subjected to high-temperature treatment for the processing of industrial solid waste BFS, which possesses a complex chemical composition. The HCPCMs were synthesized through a three-step process involving static melting, solid waste modification, and mixing–cold pressing–sintering. Then, the influence of the modification method and the amount of SiC thermal conductivity reinforced material on chemical compatibility and thermodynamic performance was explored. The results demonstrate that the predominant phase of the modified solid waste is Ca₂Al₂SiO₇, which exhibits excellent chemical compatibility with chlorine salt. HCPCMs containing less than 50 wt.% chloride content exhibit good morphological stability without any cracks, with a melting temperature of 661.76 °C and an enthalpy value of 108.73 J/g. Even after undergoing 60 thermal cycles, they maintain good chemical compatibility, with leakage rates for melting and solidification enthalpies being only 6.3% and 0.23%, respectively. The equilibrium was achieved when 40 wt.% of chloride salt was encapsulated upon the addition of 10% of SiC, and the incorporation of SiC resulted in an enhancement of thermal conductivity for HCPCMs to 2.959 W/(m·K) at room temperature and 2.400 W/(m·K) at 200 °C, with an average increase of about 2 times. The cost of the prepared HCPCMs experienced a significant reduction of 81.3%, demonstrating favorable economic performance and promising prospects for application. The research findings presented in this article can offer significant insights into the efficient utilization of solid waste. Full article

In the present study, the influence of the addition of copper (Cu) on the wear behavior of a Al-12.6Si eutectic alloy developed using the spray forming (SF) method was discussed, and the results were compared with those of as-cast (AC) alloys. The microstructural features of the alloys were examined using both optical and the scanning electron microscopy, and the chemical composition and phase identification were achieved by X-ray diffraction (XRD) analysis. The results revealed that the microstructure of binary the SF alloy consisted of fine primary and eutectic Si phases, evenly distributed in the equiaxed α-Al matrix, whereas the Cu-based SF ternary alloy consisted of uniformly distributed fine eutectic Si particulates and spherical-shaped θ-Al₂Cu precipitates, uniformly distributed in α-Al matrix. In contrast, the AC ternary (Al-12.6Si-2Cu) alloy consisted of unevenly dispersed eutectic Si needles and the coarse intermetallic compound θ-Al₂Cu in the α-Al matrix. The addition of Cu enhanced the micro hardness of the SF ternary alloy by 8, 34, and 41% compared to that of the SF binary, AC ternary, and binary alloys, respectively. The wear test was conducted using a pin-on-disc wear testing machine at different loads (10–40 N) and sliding velocities (1–3 ms⁻¹). The wear tests revealed that SF alloys exhibited an improved wear behavior in the entire applied load and sliding velocity range in comparison to that of the AC alloys. At a load of 40 N and a sliding velocity of 1 ms⁻¹, the wear rate of the SF2 alloy is 62, 47, and 23% lower than that of the AC1, AC2, and SF1 alloys, respectively. Similarly, at a sliding velocity of 3 ms⁻¹, the wear rate of the SF2 alloy is 52%, 42%, and 21% lower than that of the AC1, AC2, and SF1 alloys, respectively. The low wear rate in the SF2 alloy was due to the microstructural modification during spray forming, the precipitation of fine Al₂Cu intermetallic compounds, and increased solid solubility. The SF alloys show an increased transition from oxidative to abrasive wear, while the AC alloys demonstrate wear mechanisms that change from oxidative to abrasive, including delamination, with an increase in sliding velocity and load. Full article