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In this paper, the effects of four modification processes (B, Sr, B/Sr and B/La/Sr modification process) on the thermal conductivity and mechanical properties of base alloy (Al-7Si-0.6Fe-0.5Zn) were systematically studied. Compared with the base alloy, different modification processes could synchronously improve the thermal conductivity and integrated mechanical properties by different degree. The synchronous improvement of B/0.15La/Sr composite modified alloy was the highest among all modified alloys, and the increasing rate of thermal conductivity, elongation and UTS were 25.6%, 150.2% and 26.8%, respectively. The microstructure variation was the main reason for the synchronous improvement in thermal conductivity and integrated mechanical properties. Especially, the morphology variation of the eutectic Si phases from flak to fiber could significantly improve the thermal conductivity and integrated mechanical properties.

This study investigates the effect of hot isostatic pressing (HIPping) on the static and fatigue properties of sand-casting A356 aluminium alloys. HIPping is a method to improve the fatigue properties in aluminium cast material by reducing or eliminating the inner porosities. Investigation of the complex interaction between the microstructural features on mechanical properties before and after the HIPping process was examined using computed tomography and scanning electron microscopy (SEM). Castings generally contain pores and defects that have a detrimental impact on the fatigue properties. The HIPping process closes the porosities in all investigated samples with an increase in density. Without significant defects, the mechanical performance improved in the finer microstructure. However, a considerable variation in the results was found between the different conditions, whereas the coarser microstructure with larger porosities before HIPping showed remarkably reduced results. The high-cycle fatigue-tested samples showed reduced fatigue propagation zone in the coarser microstructure. Moreover, large cleavage areas containing bifilms in the fracture surfaces indicate that the healing process of porosities is inefficient. These porosities are closed but not healed, resulting in a detrimental effect on the static and dynamic properties.

The unsatisfactory mechanical performance at high temperatures limits the broad application of 3D‐printed aluminum alloy structures in extreme environments. This study investigates the mechanical behavior of 4 different lattice cell structures in high‐temperature environments using AlSi12Fe2.5Ni3Mn4, a newly developed, heat‐resistant, high‐strength, and printable alloy. A novel Antisymmetric anti‐Buckling Lattice Cell (ASLC‐B) based on a unique rotation reflection multistage design is developed. Micro‐CT (Computed Tomography) and SEM (Scanning Electron Microscope) analyses revealed a smooth surface and dense interior with an average porosity of less than 0.454%. Quasi‐static compression tests at 25, 100, and 200 °C showed that ASLC‐B outperformed the other 3 lattice types in load‐bearing capacity, energy absorption, and heat transfer efficiency. Specifically, the ASLC‐B demonstrated a 51.56% and 44.14% increase in compression load‐bearing capacity at 100 and 200 °C compared to ASLC‐B(AlSi10Mg), highlighting its excellent high‐temperature mechanical properties. A numerical model based on the Johnson‐Cook constitutive relationship revealed the damage failure mechanisms, showing ASLC‐B's effectiveness in preventing buckling, enhancing load‐transfer efficiency, and reducing stress concentrations. This study emphasizes the importance of improving energy absorption and mechanical performance for structural optimization in extreme conditions. The ASLC‐B design offers significant advancements in maintaining structural integrity and performance under high temperatures. A newly developed antisymmetric pyramid lattice cell is fabricated by SLM (Selective Laser Melting), and microscopic characterization is conducted using Micro‐CT (Computed Tomography) and SEM (Scanning Electron Microscope). The newAlSi12Fe2.5Ni3Mn4 alloy exhibits excellent properties in high‐temperature environments. Mechanical properties of the structures are obtained by experiments and numerical simulations under various temperatures. This article is protected by copyright. All rights reserved.

The article presents the concept of overheating the liquid AlSi17 alloy significantly above the Tliq. temperature, holding it at this temperature for a specified time, and casting it into two moulds with different cooling rates: a bentonite-based sand mould and a copper chill mould. Based on the obtained research results, it was found that overheating the AlSi17 alloy to temperatures of 920-960°C significantly improves mechanical properties, namely: tensile strength by approximately 40%, yield strength by approximately 70%, elongation by approximately 89% (for the sand mould - SM) and approximately 61% (for the copper metal mould - MM), reduction of area/ narrowness by approximately 67% (for SM) and approximately 51% (for MM) compared to the alloy without overheating. This process also reduces the scatter of the tested properties, indicating better homogeneity of the cast structure. Overheating the AlSi17 alloy to the optimal temperature range above Tliq. (in terms of the tested mechanical properties) also affects the morphology of primary silicon crystals. Such a structure, improving mechanical properties, increases the application area of hypereutectic Al-Si alloys, especially in the automotive and aerospace industries for heavily loaded castings operating under extreme thermal-mechanical stress conditions.

To fabricate a low-reflectance aluminum alloy, we have analyzed the changes in reflectance according to the morphology, components, and composition of the aluminum alloy. We find that the larger the particle size of the powder, the lower is the reflectance. This is attributed to the fact that the larger the particle size, the greater is the amount of light absorbed into the interparticle space in the powder. In addition, the reflectance decreases with increase in the Si and Mg contents, because of the lower reflectance of the strengthening phase formed in the alloy as compared to that of aluminum. In contrast, lanthanide addition causes an increase in the reflectance, which is attributed to an increase in the electrical conductivity of the alloy.

AlSi12(Fe), AlSi10Mg(Fe), AlSi10MnMg, and AlMg4Fe2 die-casting alloys were produced by high-pressure die casting (HPDC) and vacuum-assisted high-pressure die casting (VADC) under a vacuum level of 200 mbar. The chemical composition, hardness, gas and shrinkage porosity, and mechanical properties were analyzed. The parts under study were subjected to a T6 heat treatment. The VADC led to a decrease in the percentage of defects in the as-cast state for all the alloys, due to a reduction in the amount of gas porosities. After heat treatment, the quantity of gas and shrinkage porosities increased. The efficiency and level of vacuum used were not sufficient to improve the mechanical properties in the as-cast state. The ductility of AlSi10Mg(Fe) and AlSi10MnMg alloys was improved after heat treatment; however, the YS and UTS of AlSi10Mg(Fe) did not increase. The primary aluminum alloys presented higher elongation values than the secondary aluminum alloys due to the reduced amount of the needle-like β-Al5FeSi phase.

Recognizing the challenges faced by electric busses that must utilize a portion of their battery energy to heat the passenger compartment in colder locations, thus reducing their driving range, this work has devised an effective solution to this issue. A compact single‐row thermal storage system was designed to fulfill the heating needs of electric busses. Thermal resistance investigation demonstrated that this device provides exceptional insulating efficacy and heat dissipation rate. This study utilizes an aluminum‐silicon alloy as the phase transition material for heat storage, with 316 stainless steel as the encapsulating medium. Air serves as the heat exchange medium, and a numerical model has been established. A small‐scale experimental apparatus has been established to verify the accuracy of the numerical model. The study offers a comprehensive examination of the flow dynamics of the heat exchange fluid in storage tanks of varying diameters, the solidification pattern of the aluminum‐silicon alloy phase change material, and the attributes of temperature distribution. Under equal inlet temperature and flow rate conditions, increased tank diameters lead to prolonged solidification durations for the aluminum‐silicon alloy, elevated output temperatures, and a more heterogeneous temperature distribution inside the thermal storage medium. Elevating the inlet temperature in tanks of identical diameter results in increased exit temperatures and extended solidification durations for the aluminum‐silicon alloy. Conversely, maintaining a constant intake temperature while augmenting the inlet flow rate reduces the output temperature and decreases the solidification duration of the aluminum‐silicon alloy. Considering that electric busses consume a portion of their battery energy for heating the passenger cabin in cold weather, which significantly reduces their driving range, we have designed a compact single‐row heat storage device. Comparative analysis with conventional heat storage heating devices shows that this device offers superior insulation performance and heat release efficiency. We employed numerical simulation methods to analyze its heat transfer performance and developed a small‐scale experimental setup to validate the accuracy of the numerical model. Ultimately, the experimental data supported the model and revealed the heat transfer characteristics of the device.

The effects of an axial high magnetic field on the growth of the α-Al dendrites and the alignment of the iron-intermetallics (β-AlSiFe phases) in directionally solidified Al–7 wt% Si and Al–7 wt% Si–1 wt% Fe alloys were investigated experimentally. The results showed that the application of a high magnetic field changed the α-Al dendrite morphology significantly. Indeed, a high magnetic field caused the deformation of the α-Al dendrites and induced the occurrence of the columnar-to-equiaxed transition (CET). It was also found that a high magnetic field was capable of aligning the β-AlSiFe phases with the -crystal direction along the solidification direction. Further, the Seebeck thermoelectric signal at the liquid/solid interface in the Al–7 wt% Si alloys was measured in situ and the results indicated that the value of the Seebeck signal was of the order of 10 µV. The modification of the α-Al dendrite morphology under the magnetic field should be attributed to the thermoelectric magnetic force acting on the α-Al dendrites. The magnetization force may be responsible for the alignment of the β-AlSiFe phases under the magnetic field.

Corrosion properties of two Al–Si alloys processed by Rheo-high pressure die cast (HPDC) method were examined using polarization and electrochemical impedance spectroscopy (EIS) techniques on as-cast and ground surfaces. The effects of the silicon content, transverse and longitudinal macrosegregation on the corrosion resistance of the alloys were determined. Microstructural studies revealed that samples from different positions contain different fractions of solid and liquid parts of the initial slurry. Electrochemical behavior of as-cast, ground surface, and bulk material was shown to be different due to the presence of a segregated skin layer and surface quality.

Al alloy parts fabricated by powder bed fusion (PBF) have attracted much attention because of the degrees of freedom in both shapes and mechanical properties. We previously reported that the Si regions in Al-Si alloy that remain after the rapid remelting process in PBF act as intrinsic heterogeneous nucleation sites during the subsequent resolidification. This suggests that the Si particles are crucial for a novel grain refinement strategy. To provide guidelines for grain refinement, the effects of solidification, remelting, and resolidification conditions on microstructures were investigated by multiphase-field simulation. We revealed that the resolidification microstructure is determined by the size and number of Si regions in the initial solidification microstructures and by the threshold size for the nucleation site, depending on the remelting and resolidification conditions. Furthermore, the most refined microstructure with the average grain size of 4.8 µm is predicted to be formed under conditions with a large temperature gradient of Gsol = 106 K/m in the initial solidification, a high heating rate of HR = 105 K/s in the remelting process, and a fast solidification rate of Rresol = 10−1 m/s in the resolidification process. Each of these conditions is necessary to be considered to control the microstructures of Al-Si alloys fabricated via PBF.