Al Si Research Articles

Elucidating photoluminescent properties of Eu‐doped Ca–Al–Si–O(–N) glasses and the local structures of Eu ions

AbstractEuropium (Eu) ion–doped luminescent materials have attracted considerable attention for their numerous optical applications. Eu‐doped Ca–Al–Si–O(–N) glasses were synthesized from a mixture of oxynitride glasses and Eu2O3 powder using a standard melt‐quenching technique in a radiofrequency furnace. The source Eu trivalent ions primarily changed to Eu2+ during melting, and the ratio of Eu2+ ions increased with an increase in Eu content in the starting mixture. All the prepared glasses exhibited photoluminescence (PL) owing to the 5d–4f transition of Eu2+ ions. The absorption edge and PL wavelength shifted to longer wavelength with an increase in Eu content. Moreover, oxynitride glasses exhibited a longer wavelength than those of oxide glasses. The internal quantum efficiency (IQE) increased with the increase in Eu content until it reached a maximum. X‐ray absorption structure and electron spin resonance spectroscopies were used to determine the local structure of Eu ions, which confirmed that changes in the local structure of Eu ions were responsible for the shift in PL peak and the change in IQE. The development of the Eu‐doped Ca–Al–Si–O–N glasses is highly inspiring for transparent phosphors.

Boosting the grain refinement of commercial Al alloys by compound addition of Sc

For decades, Al–Ti–B has been widely used for refining commercial Al alloys. However, the addition of Al–Ti–B master alloys to recycled Al alloys suffers from Si-poisoning and cannot achieve desired refinement and thus final strength-ductility. In this study, a novel grain refiner made of Al–Ti–B-Sc has been developed and its application in refining recycled Al–Si–Cu alloys has been quantified using X-ray computed tomography (XCT). It has been found that the new Al–5Ti–1B-0.8Sc master alloy exceed the performance of Al–5Ti–1B in three aspects: (1) formation of Al3(Sc,Ti) heterogeneous nucleation particles other than Al3Ti; (2) dispersing TiB2 by forming TiB2/Al3(Sc,Ti) clusters and increasing Al melt viscosity; (3) reducing the specific surface area of Al3Ti to improve its high-temperature stability. Surprisingly, the compound addition of Sc has been found to further reduce the grain and Si particle size due to accelerated kinetics of α-Al nucleation and diminished Si poisoning. Therefore, this study proposes not only a new master alloy but also a new grain refinement method, which can effectively increase the tensile strength and elongation of recycled Al alloys up to 433.2 ± 10.5 MPa and 3.0 ± 0.1 %, respectively.

Study on physical property regulation and high-temperature heat storage properties of Al–Si composite phase change materials prepared by one-step pressing

In this paper, we investigate a metal composite prepared using a one-step pressing method, where Al–Si alloy acts as the phase change materials (PCMs) and Al2O3/AlN serve as the structural support materials. The alloy formation and PCM composite preparation are synthesized in a single step. The study aims to characterize the microstructure, thermodynamic, and thermal properties of the composite material. To assess the heat storage properties of the prepared composite PCMs at temperatures higher than 600 °C, a high-temperature test system is established using a high-frequency induction heater. Additionally, we explore how to improve the issue of liquid leakage under high-temperature conditions. The results demonstrate that Al2O3 and AlN (ceramic materials) exhibit excellent chemical compatibility with Al–Si composite PCMs. After sintering, the ceramic materials form a strong bond with Al–Si, effectively retaining the liquid phase of Al–Si alloy within the composite material. Consequently, the Al–Si composite PCMs do not exhibit high-temperature liquid leakage under elevated conditions. Both Al2O3/Al–Si and AlN/Al–Si composites possess favorable high temperature heat storage properties. The phase change enthalpy of Al2O3/Al–Si composite reaches 400 kJ/kg, with a thermal conductivity of 36 W/(m·K). Similarly, the AlN/Al–Si composite achieves a phase change enthalpy of 404 kJ/kg and a thermal conductivity of 43 W/(m·K). Both composites fulfill the requirements for high-temperature heat storage applications.

Evaluating the Impact of Fly Ash Content on the Dry Sliding Wear Behaviour of Al–Si–Mg–Cu Metal Matrix Composite for Lightweight Application

Evaluating the Impact of Fly Ash Content on the Dry Sliding Wear Behaviour of Al–Si–Mg–Cu Metal Matrix Composite for Lightweight Application

Вплив температурноспричинених змін будови розплаву системи Al–Si на структуру і електричний опір сплаву в твердому стані

According to the results of previous studies, it was found that the temperature dependence of electrical resistance during heating of the Al + 17,6 % Si melt curve characterized by presence of several sharp inflections. This gave grounds for asserting possibility of temperature-induced changes in structure of specified system melts. However, it remains an open question whether the changes that occurred when melt was overheated are preserved during subsequent cooling. The problem of effect of temperature-induced changes in Al–Si melts structure on the structure and properties of the alloy in the solid state also requires a more detailed study. Resistometric studies of melt were carried out according to the method [1]. The ability to preserve temperature-induced changes in melt was assessed by electrical resistance value during cooling of the overheated Al + 17,6 % Si melt at five characteristic temperature values. To avoid errors cozied by imbalance, only results obtained after stabilization of melt resistance at a given temperature were taken into account. Temperature-induced changes in melt structure were evaluated by structure of solid samples obtained by quenching from the liquid state. The nature of influence of changes that occur when the melt is overheated on solid alloy structure and properties was determined by specific electrical resistance values and material microstructures of samples obtained after melt isothermal holding at temperatures of 720 °C, 880 °C, 960 °C and 1050 °C. The presence of electric resistance significant hysteresis can indicate that the changes that occurred during melt overheating are preserved during its cooling. It was also established that the specified changes affect to properties (in particular, specific electrical resistance) and the microstructure of the solid alloy (first of all, the melt overheating affects to size of primary silicon particles). Keywords: aluminum, silicon, thermodynamic equilibrium, melts, electrical resistance.

Microstructure evolution and strengthening mechanism of A356/Al-X-Ce(Ti, C) system by inoculation treatment

In recent decades, grain refiners had not only improved the properties on cast aluminum alloy, but also changed the application field of cast aluminum alloys, which had attracted widespread attention. However, there were few reports on microstructure evolution of A356/CRE Al-X-Ce(Ti, C) system by combining traditional grain refiners with element Ce. In this study, refined A356 alloys with excellent strength and plasticity were obtained by adding CRE Al-X-Ce(Ti, C) (0, 0.4, 0.8, 1.2, 1.6 and 2.0 wt%, respectively). Using XRD, SEM and TEM, the morphology of phases in the refined A356 alloy and phases of grain refiner were identified. The microstructure evolution of α-Al grains and eutectic Si with the introduction of TiC and Ce was analyzed. The results showed that the novel CRE Al-X-Ce(Ti, C) could not only effectively refine α-Al grains, but also modify Si microstructure of the alloy. The refined A356 alloys with excellent strength and plasticity were obtained with 2.0 and 1.6 wt% grain refiner (CRE) additions, respectively. TiC as nucleation particle and Ce as the surfactant refined the α-Al grains. Also, Ce modified eutectic Si by changing the way it grows. When the CRE Al-X-Ce(Ti, C) content researched 2.0 wt%, the long plate-like Al–Si–Ce phase was formed which can easily caused cracks and reduced the elongation of alloy.

Effect of Alloying Elements Mg and Cu on the Modification of Eutectic Silicon in Hypoeutectic Al–Si Alloys

The modification of eutectic silicon plays a crucial role in enhancing the mechanical properties of hypoeutectic Al–Si alloys. However, there is still limited understanding regarding the factors that affect the modification of eutectic silicon in hypoeutectic Al–Si alloys, particularly in terms of the role played by alloying elements during the modification process. In order to address this gap, this study aimed to investigate the influence of two key alloying elements, Mg and Cu, on the modification effect of Sr. To achieve this, the morphology of eutectic silicon in the as-cast and heat-treated states of Al–7Si alloy, modified with Sr, was examined using scanning electron microscopy (SEM). Different levels of magnesium and copper content were used to analyze their impact on the modification effect of Sr. The results obtained from the analysis revealed that both Mg and Cu significantly weaken the modification effect of strontium on eutectic silicon. Furthermore, it was observed that the degree of deterioration in the modification effect increases progressively with higher alloying element content. Interestingly, increasing the strontium content and adjusting the cooling rate were found to be ineffective in eliminating this weakening effect caused by Mg and Cu. These findings highlight the complex interplay between alloying elements and the modification process of eutectic silicon in hypoeutectic Al–Si alloys. A deeper understanding of these factors is essential for the development of effective strategies to optimize the mechanical properties of such alloys.

Refining Al–20Si Alloy by Appending Trace Sr–Sc–Ce Nanoparticles and Ultrasonic Vibration Processing

In this study, Al–20Si alloy is modified by appending trace Sr–Sc–Ce nanoparticles and ultrasonic vibration processing (UVP). The consequences indicate that its microstructure is significantly refined and its mechanical characteristics are improved. The effect of the favorable refinements is achieved by appending 0.2% Sr–0.15% Sc–0.3% Ce and performing UVP. The primary Si is the minimum, the grain roundness coefficient and the strength of extension are the maximum, and the spheroidizing effect of α‐Al is the best. The elongation and hardness are the highest when 0.4% Ce is appended. The research consequences afford a reasonable process scheme for manufacturing high‐quality wear‐resistant material of the automotive and aerospace industries.

Microstructure and mechanical properties of adjustable-ring-mode laser welded and hot-stamped Al–Si coated boron steel joints

The microstructure and mechanical properties of adjustable-ring-mode (ARM) laser-welded, hot-stamped 22MnB5 steel joints were analyzed and compared with those of Al–Si coated 22MnB5. Al segregation into the fusion zone (FZ) was suppressed by a ring beam introduced via ring-beam-mode (RBM) and dual-beam-mode (DBM) laser welding. Dilution of the Al–Si coating in the FZ induced α-ferrite formation during hot stamping. After hot stamping, the α-ferrite fraction in the FZ decreased (from 23 vol% to 4.27 vol%) more than that in the center-beam-mode (CBM) welded joints owing to the ring beam. Electron backscattered diffraction analysis indicated the distribution of high-density and uniform geometrically necessary dislocations, which caused coordinated deformation in the martensite grains, in the RBM and DBM FZs. The average microhardness in the FZ in the tailor-welded blank (TWB) joints was ∼30–40 HV lower than that in the RBM and DBM welded base metal (480 HV) and that in the FZ of the CBM reduced to 295 HV because of the formation of a large amount of ductile α-ferrite. The tensile strength and elongation of the TWB joint in the CBM were ∼989 MPa and 1.1 %, respectively, which were significantly lower than those of the RBM (1245 MPa and 1.96 %, respectively) and DBM (1321 MPa and 2.12 %, respectively). Finally, the 22MnB5 steel sheets were subjected to ARM laser welding without removing the coating layer to evaluate the effect of the ring beam on Al segregation suppression in the FZ and mechanical properties of the TWB joints.

Anomalous Behaviour of Nb in the Formation of Fe-Rich Intermetallics in Al–Si–Fe-Type Alloy

Anomalous Behaviour of Nb in the Formation of Fe-Rich Intermetallics in Al–Si–Fe-Type Alloy

Effect of T6 heat treatment on microstructure and mechanical properties of Al–18Si–10Cu–10Ni–5Mn–5Mg alloy prepared by laser-directed energy deposition

The new aluminum alloy Al–18Si–10Cu–10Ni–5Mn–5Mg (wt.%) prepared by laser-directed energy deposition (L-DED) process has excellent mechanical strength but poor ductility. In this paper, a T6 heat treatment is applied to it, aiming at the improvement of the material's ductility. The results show that after the T6 heat treatment, the original fine microstructure of the material is destroyed, and the phase composition changes. However, it is found that the formation of the nano-strengthened θʹ phase and the clear crystal orientation relationship between the θʹ phase and the α-Al matrix make the θ′ phase form a continuous grain boundary in the Al matrix, thus enhancing the strength and hardness of the alloy. It is worth noting that the microhardness is reduced slightly, but the residual stress is almost completely eliminated. The experimental results of mechanical properties show that the tensile strength and compressive strength of the material are reduced by 12 % and 17 % respectively after T6 heat treatment, but the ductility of the material is increased by 1.3 times, which is mainly attributed to the change of strengthening mechanism and the large and uniform second phase.

Effect of Mn and B Addition on the Microstructure and Properties of Al–Si–Cu–Mg Cast Alloy

Effect of Mn and B Addition on the Microstructure and Properties of Al–Si–Cu–Mg Cast Alloy

Nanoscale Reconfigurable Si Transistors: From Wires to Sheets and Unto Multi‐Wire Channels

AbstractIn this work, bottom‐up Al–Si–Al nanowire (NW) heterostructures are presented, which act as a prototype vehicle toward top‐down fabricated nanosheet (NS) and multi‐wire (MW) reconfigurable field‐effect transistors (RFETs). Evaluating the key parameters of these transistors regarding the on‐ and off‐currents as well as threshold voltages for n‐ and p‐type operation exhibit a high degree of symmetry. Most notably also a low device‐to‐device variability is achieved. In this respect, the investigated Al–Si material system reveals its relevance for reconfigurable logic cells obtained from Si NSs. To show the versatility of the proposed devices, this work reports on a combinational wired‐AND gate obtained from a multi‐gate RFET. Additionally, up‐scaling the current is achieved by realizing a MW RFET without compromising reconfigurability. The Al–Si–Al platform has substantial potential to enable complex adaptive and self‐learning combinational and sequential circuits with energy efficient and small footprint computing paradigms as well as for native components for hardware security circuits.

A Complete Strategy to Achieve High Precision Automatic Segmentation of Challenging Experimental X‐Ray Computed Tomography Data Using Low‐Resemblance Synthetic Training Data

It is shown that preconditioning of experimental X‐ray computed tomography (XCT) data is critical to achieve high‐precision segmentation scores. The challenging experimental XCT datasets and deep convolutional neural networks (DCNNs) are used that are trained with low‐resemblance synthetic XCT data. The material used is a 6‐phase Al–Si metal matrix composite‐reinforced with ceramic fibers and particles. To achieve generalization, in our past studies, specific data augmentation techniques were proposed for the synthetic XCT training data. In addition, two toolsets are devised: (1) special 3D DCNN architecture (3D Triple_UNet), slicing the experimental XCT data from multiple views (MultiView Forwarding), the i.S.Sy.Da.T.A. iterative segmentation algorithm, and (2) nonlocal means (NLM) conditioning (filtering) for the experimental XCT data. This results in good segmentation Dice scores across all phases compared to more standard approaches (i.e., standard UNet architecture, single view slicing, standard single training, and NLM conditioning). Herein, the NLM filter is replaced with the deep conditioning framework BAM SynthCOND introduced in a previous publication, which can be trained with synthetic XCT data. This leads to a significant segmentation precision increase for all phases. The proposed methods are potentially applicable to other materials and imaging techniques.

Effect of reaction temperature and holding time on the interfacial microstructure of Al–Si–Mg/Cu bimetals manufactured by hot-dip aluminizing

This study investigates the effects of reaction temperature and holding time on intermetallic compounds (IMCs) at the Al–Si–Mg/Cu bimetals interface fabricated by hot-dip aluminizing. Previous research has demonstrated that the presence of IMC layers in Al–Si–Mg/Cu bimetals significantly increased the interface hardness. This study aims to achieve a continuous change in hardness at the interface by forming Cu3Al layers, thus exhibiting the lowest hardness and highest ductility among the Al–Cu IMCs. The thickness and morphology of the Al–Cu IMC layer depend on the reaction temperature and holding time. Al–Cu intermetallic phases with higher Cu contents, such as Cu3Al, Cu9Al4, Cu3Al2, CuAl, and CuAl2, were closer to the Cu surface. The formation of Cu3Al leads to continuous changes in the hardness of the Cu and IMC layers. Furthermore, the growth kinetics of IMCs and their formation mechanisms are discussed. The results indicate that hot-dip aluminizing is an effective method for controlling the composition and thickness of the IMC layer to achieve a continuous change in the interfacial hardness.

Reactivity of kaolinitic clays calcined in the 650 °C–1050 °C temperature range: Towards a robust assessment of overcalcination

Using calcined clays as supplementary cementitious materials is one of the main solutions available for a substantial and widespread reduction of the clinker factor in cement. Thus, understanding the phenomena governing their production process and reactivity is crucial for a successful technological deployment. In this study, the mineralogical and physical changes experienced by kaolinitic clays calcined within 650 and 1050 °C were explored, with emphasis on the identification of overcalcination. It was observed that the decrease in reactivity above the optimum calcination temperature is associated with the formation of Al–Si spinel and a decrease in specific surface area, which is linked to a modification of the pore size distribution within the particles. Differential scanning calorimetry (DSC) was identified as the most robust, and repeatable technique to identify an overcalcined kaolinitic clay. In combination with thermogravimetric analysis (TGA), it can provide a complete calcination process overview, relevant for quality control purposes.

Вивчення взаємодії інфрачервонопрозорих матеріалів ZnSe, ZnS, Si, Ge з розплавами металів

Wetting of infrared-transparent materials — selenide and sulfide zinc, germanium, and silicon by metal melts in a vacuum in a wide temperature range was studied by the sessile drop method using the method of capillary purification of the drop melt during the experiment. Pure metals In, Sn, Pb, Al, Fe, Ni, binary Al—Si, Ge—Si, In—Cu and multicomponent In—Sn—Cu—Ti alloys were used. When zinc chalcogenides are wetted with In—Sn—Cu—Ti melts, zinc selenide is wetted better than zinc sulfide. This is due to the lower thermodynamic stability of selenide. In systems where copper is present in melts, wetting is affected not only by the interaction of selenium or sulfur with titanium, but also by the interaction of copper and zinc (in the copper-zinc system, solid solutions of copper and zinc are formed and copper dissolves in solid zinc). This conclusion also confirms the wetting of the substrate by the In—Cu melt. The values of the contact angle at 650 C are equal to 32, which is less than for the In—Sn—Ti melt at the same temperature. It can be said that for such a system, the interaction of zinc with copper is very important, which is not inferior to the wetting effect of the interaction of chalcogens with titanium. The wetting of single crystals of germanium and silicon by metal melts improves with increasing temperature. Iron and nickel wet silicon (contact angles close to zero) at temperatures lower than their melting point. Contact melting also occurs when silicon substrates are wetted with aluminum melts (the eutectic in the Al—Si system has a temperature of 577 °C). Germanium is better wetted by tin than by indium and lead. Technological processes of soldering infrared transparent materials with metals were developed and soldered joints were obtained. Keywords: infrared transparent materials, polycrystalline zinc selenide and sulfide, single crystals of germanium and silicon, wetting, soldering.

Effect of Annealing on Microstructure and Mechanical Properties of Al–18Si Alloy Cast by Melt Quenching

Effect of Annealing on Microstructure and Mechanical Properties of Al–18Si Alloy Cast by Melt Quenching

Microstructure and properties of Al–Si functionally graded materials for electronic packaging

Two- and three-layer Al–Si functionally graded materials (FGMs) for electronic packaging were prepared by spray deposition. The results show that dense microstructure and good interlayer bonding are obtained in the FGMs. The flexural strength of the three-layer FGMs is higher than that of the two-layer FGMs, and the flexural strength in the H–L direction with high Si content layer as the bearing surface is higher than that in the L–H direction with low Si content layer as the bearing surface. The thermal conductivity of all the FGMs exceeds 140 W/(m·K), and the coefficient of thermal expansion (CTE) shows no significant difference. After thermal shock treatment, more and larger cracks are found in the two-layer FGM than in the three-layer FGMs. This phenomenon is due to the high thermal stress at the interfaces and the tendency of large Si particles to rupture as a result of stress concentration.

Study on Preparation of Hypoeutectic Al–Si Alloy from Diamond Wire Saw Silicon Powder by Electromagnetic Method

Study on Preparation of Hypoeutectic Al–Si Alloy from Diamond Wire Saw Silicon Powder by Electromagnetic Method