Molten Al Alloy Research Articles

Microstructure and mechanical properties of SiCf/SiC–AlN composites prepared by low temperature reactive melt infiltration

In this work, SiCf/SiC–AlN composites were fabricated by low temperature reactive melt infiltration of Si–Al alloy into porous SiCf/C–Si3N4 preforms prepared through slurry brushing. The effect of the preforms pore structure on the melt infiltration was studied, and the erosion behaviors of Si–Al alloy melt on the fibers and the interphases were investigated. The results indicate that the preforms with smaller pore size can hinder the alloy melt infiltration, making it difficult for the infiltration process to proceed adequately. In contrast, when the preforms with larger pore size are utilized, the alloy melt can completely infiltrate into the preforms and form dense SiC–AlN matrix in the intra-fiber bundle by in-situ reaction. Moreover, the bending strength of the composites derived from larger pore size preforms could reach 160.2 MPa, which is about 1.5 times higher than that of the composites derived from smaller pore size preforms. In addition, the damage of the SiC interphase caused by the preforms preparation aggravates the erosion of the internal BN interphase and SiC fibers by Al melt. The eroded interphases and fibers could adversely affect the mechanical properties of both composites. This study lays the foundation for the preparation of the composites with excellent properties.

Effects of Main Alloying Elements on Interface Reaction between Tool Steel and Molten Aluminum

Effects of Si and Mg as main elements on interface reaction between tool steel and molten Al alloy at 700°C were investigated. Pure aluminum and Al-10mass%Mg alloy showed relatively simple interfacial layers, whereas thicker, multi-layered reaction bonds were found in the diffusion couple of A380 alloy. The diffusion of a large amount of Fe into Al matrix throughout the interfacial layer led to the formation of Al-Fe based intermetallic particles in the Al base metals. The diffusion couple of Al-10mass%Mg alloy showed a similar intermetallic layer as that of pure Al, indicating that 10mass%Mg in the Al melt rarely affected the formation of Al-Fe intermetallic layers. However, A380 alloy showed much expanded soldering area and increased thickness of intermetallic layers. Based on the phase diagram calculated, the solubility of Fe in liquid Al increased significantly with increasing Si content up to apploximately 5mass%, while, in the case of 10mass%Mg addition, the Fe solubility gradually decreased with increasing Mg content. Al-10mass%Mg alloy also showed the same tendency as that of pure Al in the formation and distribution of intermetallic compounds. However, in the Al-12mass%Si alloy, two types of Al-Fe-Si ternary compounds are present on the Al-rich side.

Numerical simulation of physical field during different ultrasonic power assisted casting of 7085 aluminum alloy

High‐energy ultrasound has the effect of purifying the aluminum (Al) melt and improving the uniformity of temperature and flow field distribution. In this paper, a finite element numerical model of ultrasonic‐assisted casting of 7085 Al alloy melt was established, and the changes of acoustic pressure field, temperature field and flow field in the solidification process of alloy melt with different ultrasonic power were investigated. The numerical simulation results show that the thickness of the 7085 Al melt mushy zone decreases by 89 mm, 97 mm, 108 mm, 114 mm and 99 mm, respectively, compared without ultrasonic (WNU) when the ultrasonic power was 150 W, 350 W, 550 W, 750 W and 950 W. The area of the alloy mushy zone increases by 38.1%, 43.5%, 61.0%, 206.5% and 45.6%, respectively. According to numerical simulation results, when the ultrasonic power was 750W, it had the best effect on improving the macroscopic physical field, increasing the mass and heat transfer rate in the center of the Al melt. Meanwhile, the experimental results of industrial melting and casting of 7085 large‐scale Al alloy ingots were basically consistent with the numerical simulation, which provided technical support for ultrasonic‐assisted fabrication of large‐scale 7085 Al alloy ingots.This article is protected by copyright. All rights reserved.

Role of Si Addition in Interfacial Reactions of Steel Sheets Hot-dipped in Zn-55%Al Alloy Melt

Role of Si Addition in Interfacial Reactions of Steel Sheets Hot-dipped in Zn-55%Al Alloy Melt

The corrosion resistance of maraging steel 1.2709 produced by L-PBF in contact with molten Al-alloys

Nowadays there is a growing interest in the use of secondary Al-alloys for high-pressure die casting to obtain structural parts. To guarantee appropriate performance, these alloys are characterized by a lower Fe content (< 0.15%) than conventional secondary ones, commonly used in the production of non-structural parts. This makes them more susceptible to the phenomenon of die-soldering, thus resulting in a decrease in the service life of dies and inserts. The production of complex and demanding castings requires appropriate dies and materials, especially in high stressed areas where higher-performance steel inserts are used. Recently, maraging steel has been applied for these issues. Thanks to the good weldability of maraging steels, these alloys are nowadays also processed by additive manufacturing (AM) techniques, to obtain very complex parts like inserts with conformal cooling channels, able to extend the life of the inserts themselves, increasing productivity. In this context, this work aimed at the evaluation of the dissolution of maraging steel (1.2709) samples obtained via laser-based powder bed fusion (L-PBF) into molten AlSi7Mg (B356.2) through static immersion tests carried out at 720°C for different times, to evaluate their response to the die-soldering phenomenon. For comparison, forged maraging steel samples were also considered, to investigate the effect of the different microstructure on the dissolution behavior. As well as a conventional H11 steel, to obtain benchmark data. The corrosion resistance of the samples was evaluated by measuring the samples’ dimensional variation after the tests. Furthermore, SEM-EDS analysis was carried out to investigate the extent and the composition of the intermetallic layer formed on the samples’ surface.

Fast reactive interdiffusion between solid brass and liquid aluminium

The formation mechanisms of intermetallic layers and the development of the interface between solid brass and molten Al alloy were experimentally investigated using semi-infinite solid-liquid diffusion couples. Isothermal annealing of commercial CuZn37 – AA7075 diffusion couples was conducted for the selected temperatures of 650 °C, 660 °C, 680 °C and 700 °C, for three annealing times of 10 s, 20 s and 40 s, followed by quenching. Regardless of the temperature, the interface consisted of three intermetallic layers that are reaction products as defined in the Al–Cu–Zn phase diagram. In order to explain the growth behaviour and bring insights into the interface formation mechanisms, the thermodynamics of the Al–Cu–Zn was investigated by CALPHAD (calculation of phase diagrams). Based on these ex-situ results, three distinct phenomena were observed. First, intermetallic layers dissolve simultaneously into the molten Al alloy when the annealing time exceeds 40 s. Second, parts of the intermetallic layer that are in contact with the molten Al, detach from the interface region in the direction of molten Al alloy leading to a decrease in the layer thickness and deviation from planar-like geometry. Third, the formation of the three intermetallic layers is exclusively the result of solid-liquid interactions followed by quenching. Previous studies have shown a scattered interface character between solid brass and molten aluminium which results from interactions in the solid-solid state due to low cooling rates. As a result, the concept of primary intermetallic layers was introduced to describe the interface formation upon the contact of solid brass with molten aluminium alloy.

Investigation of the rate-controlling process of intermetallic layer growth at the interface between ferrous metal and molten Al–Mg–Si alloy

In this study, we focused on unraveling the intricate world of intermetallic compound formation at the interface of solid Fe and liquid Al–Mg–Si alloy. Our primary aim was to shed light on the phenomenon of Fe degradation in molten Al alloys. Our investigation led us to discover two distinct intermetallic phases, namely Fe2Al5 and Fe4Al13, each exhibiting unique growth dynamics influenced by the interplay of volume diffusion and interface reactions. Moreover, delving deeper into the mechanics of these processes, we meticulously analyzed the rate-controlling mechanisms governing layer growth, exploring both volume diffusion and interface reactions. Furthermore, we quantified the activation enthalpy associated with these phenomena, enriching our understanding of the energy barriers involved in atom or molecule diffusion across solid-liquid interfaces. The implications of our findings extend far beyond the confines of the laboratory, holding significant promise for real-world applications. These insights into Fe degradation prevention and the enhancement of Al alloy performance when in contact with Fe materials offer exciting prospects for materials design and process optimization across diverse engineering and industrial domains.

Evaluation of reactive wetting kinetics of carbon fibers by molten Al-Ti alloy and its application to the fabrication of Al/carbon fiber composites

Wetting and interfacial reactions between molten Al and carbon fibers (CFs) are crucial for the fabrication of high-thermal conductive Al/CF composites through liquid-state processes including casting. The formation of Al4C3 which has a low thermal conductivity and high reactivity with water needs to be suppressed while improving wettability. The addition of Ti into molten Al forms TiC and contributes to significant improvement in wettability. To control a thin morphology of TiC, the kinetics of reactive wetting need to be clarified. In the present study, the reactive wetting kinetics between molten Al or Al-Ti alloy and pitch-based CF were investigated using the dipping coverage method combined with microstructural observations. The addition of Ti into molten Al drastically accelerated the wetting and reduced the apparent activation barrier for reactive wetting, which was related to the change in the interfacial products from the Al4C3 phase to the TiC phase. The Al4C3 phase grew while eroding the CFs, whereas the TiC phase formed in a thin-layered morphology around CFs and suppressed the diameter reduction of CF. The reduction in the apparent activation barrier and the morphology of carbides indicated a change in the dominant phenomena for reactive wetting from Al4C3 growth to TiC formation (controlled by diffusion in liquid Al). Based on the kinetics evaluations, CF were hybridized with pure Al and Al-Ti alloy through a casting process, and their thermal conductivities were evaluated. The addition of CF into pure Al degraded the thermal conductivity due to the eroded CF and coarsened Al4C3 phase, whereas the addition of CF into Al-Ti alloy enhanced the thermal conductivity. This study provides new insights into reactive wetting phenomena related to the fabrication of high-thermal conductive metal matrix composites.

Grain-refining effects and mechanism of novel Al-Nb-B refiner on Al-Mg-Si alloy: phase-field simulation and experiment study

In this paper, the grain-refining effect of Al-Nb-B refiner in wrought Al alloys and corresponding refining mechanism was investigated using phase-field simulation and experiment methods. Through experimental statistics and data correction, the seed radius introduced by Al-Nb-B refiner into Al alloy melt and the corresponding quantitative density distribution data were obtained, and a seed density model (SDM) model has been established. On this basis, a multi-phase field method (MPFM) combined with the calculation of phase diagram (CALPHAD) has been employed to simulate the α-Al grain evolution of Al-Mg-Si alloy during the solidification process with the help of thermodynamic database. Experimental studies showed that the addition of 0.03 wt% Nb (Adding by Al-1.93Nb-0.22B master alloy) significantly reduced the grain size from 956.4 μm to about 219.4 μm, and the grain size slowly decreased to 192.3 μm by continuing to add refiner to 0.09 wt% Nb. Meanwhile, the simulation results demonstrated that after the addition of refiners, dendrite morphology transformed from the relatively developed dendrites with secondary and tertiary dendrites to a fine and uniform equiaxed shape. Simulation and experimental studies showed quantitative agreement. In addition, the results also prove that the addition of Al-Nb-B refiner can provide high-quality and stable heterogeneous nucleation particles.

In-situ tailoring microstructure by directly synthesized TiC–TiB2 nanoparticles to achieve well-balanced strength and ductility in Al–Cu alloy

Incorporating and dispersing trace manipulated agents into Al alloy melt is a longstanding challenge that hinders the balance of strength-ductility in cast Al alloys. A delicate strategy of in-situ fabrication and effective incorporation of the tuned agents was put forward in this study to achieve a better-optimized microstructure of Al-5.5Cu alloys with superior room-temperature and high-temperature mechanical performance. The tailored microstructure effects and optimized mechanical properties under room temperature and elevated temperature (220 °C) by varying mole ratios of dispersed TiC–TiB2 particles were investigated. The in-situ TiC–TiB2 nanoparticles with the mole ratio in 1 : 2 (TiC: TiB2) performed the best microstructure tailoring capacity for Al–Cu-based alloy, which the manipulated alloys shows the most refined and homogeneous grain microstructure with a size of 40.4 μm, compared with the based Al–Cu alloy, refined by 73.8%. Also, the segregation of Cu was mitigated and after heat treatment, the transformation of θ″ → θ′ was accelerated. Thanks to the contribution of TiC–TiB2 particles, Al–Cu alloys perform excellent strength and ductility synergy both at room temperature and elevated temperature, and the strengthening mechanism was also discussed. It is believed that this work can give an optimized strategy from the in-situ synthesis, incorporation and dispersion of manipulated agents to the alloy microstructure tailoring and strength-ductility balancing.

On the mechanism of Si-promoted destabilization of TiCx particles in Al alloys

TiCx is an excellent composite strengthening particle and grain refiner for Al alloys. However, the stability of TiCx is poor when solute Si exists in Al alloy melts, which significantly depresses its strengthening and grain refining effects. In this work, the destabilization mechanisms of the TiCx particles in Al-Si alloy melt with a composition of Al-7Si-7.5TiC were explored via experiments, first-principles calculations and thermodynamic calculations. The experimental results show that Si atoms diffuse into TiCx and Ti atoms are released into the Al melt to form a Ti-rich transition zone during the insulation of TiCx in Al-Si melt, and the TiAlySiz and Al4C3 phases are solidified in the Ti-rich zone and at Ti-rich zone/TiCx interface, respectively. The first principles calculations show that the low formation energy of C vacancies facilitates the rapid diffusion of Si atoms in TiCx, while the doping of Si atoms reduces the energy barrier of diffusion of Ti atoms in TiCx and promotes the formation of Ti-rich zones. The thermodynamic calculations show that the wide crystallization temperature range of the destabilized product TiAlySiz phase is the key to continuous decomposition of TiCx particles. In addition, the driving force of the main destabilization reaction of TiCx in the Al-Si alloys is about 44 times higher than that in the Al alloys without Si addition. This indicates that the presence of solute Si remarkably promotes the subsequent decomposition process of TiCx in the Al-Si alloy melts.

Extraction of Al from Coarse Al-Si Alloy by The Selective Liquation Method.

A selective liquation process to extract Al from a coarse Al–Si alloy, produced by carbothermal reduction, was investigated on the laboratory scale. The products obtained by selective liquation–vacuum distillation were analyzed by X-ray diffraction, inductively coupled plasma optical emission spectrometry and scanning electron microscopy. During the selective liquation process with the use of zinc as the solvent, the pure aluminum in the coarse Al–Si alloy dissolved in the zinc melt to form an α-solid solution with zinc, and most of the silicon and iron-rich phases and Al–Si–Fe intermetallics precipitated and grew into massive grains that entered into the slag and separated with the Zn–Al alloy melt. However, some fine silicon particles remained in the Zn–Al alloy. Thus, Al–Si alloys conforming to industrial application standards were obtained when the Zn–Al alloys were separated by a distillation process.

Metallothermic Production of Aluminum–Strontium Master Alloy for Modification of Silicon

Strontium master alloy is widely used in today’s aluminum foundries for modification of Al–Si alloys. In this study, Al–Sr master alloy was produced in molten Al alloy directly from strontium carbonate instead of using the pure strontium metal which is difficult to store in the air due to its high oxygen affinity. In a laboratory-scale induction furnace, SrCO3 and SrO powders were injected into the liquid metal via argon flow and subjected to reduction reaction. The oxygen-free medium required for the reduction was provided by the gas purged on both the surface and the inside of the liquid metal. Hence, the master alloy was produced directly by an economical process. Moreover, the addition of Mg to the reducing melt decreased the surface tension of the liquid aluminum; as a result, the reduction efficiency was increased. At the best of the results, the master alloy containing 5.15% Sr was obtained by reducing approximately half of the fed SrO by Al6Mg. This master alloy was used to modify A360 alloy, and the same modification effect as the commercial Al5Sr master alloy was observed.

Novel MgHf4P6O24 as a Solid Electrolyte in Mg-Sensors

In this study, a modified sol-gel chemical route was developed for synthesising MgHf4P6O24 multicomponent nanostructured ceramic oxide electrolytes. The chemical synthesis approach was determined by substituting the Zr4+ B-site in MgZr4P6O24 solid electrolyte [1-3] with Hf4+ reactive oxide, resulting in a considerably low activation energy (Ea = 0.74 ± 0.04 eV) and a promising ionic conductivity (4.52 x 10-4 Scm-1 at 747oC), for the novel MgHf4P6O24 solid electrolyte.The solid electrolyte was first calcined at a relatively low temperature range of 800-900oC, while the resultant calcined nanopowders were pressed into pellets of 13mm diameter (Ø) and 3.8mm thickness using a uniaxial steel press at 5kN compressive pressure. The pressed pellets were later sintered at 1000 ≤ T/oC ≤ 1550 temperature range. Meanwhile, calcination and sintering temperatures of the electroceramic electrolytes were maintained at 900 ≤ T/oC ≤ 1300oC after TGA-DSC thermal analysis and densification measurements; An optimum density and stable thermodynamic composition of the solid oxide pellets were also achieved at 1300oC. X-ray diffraction and rietveld analysis reveals a good crystallinity of the solid electrolyte with an average crystallite size of 20±2 nm and 42±2 nm at 800oC and 900oC, respectively, this indicates that crystallite size increases as a function of calcination temperature, which is consistent with the TGA-DSC thermal analysis profiles and confirmed using HRTEM. Interestingly, the refined crystallographic data and conductivity properties of the novel MgHf4P6O24 solid electrolyte characterised in this study was reported for the first time. The MgHf4P6O24 solid electrolyte characterised for their electrical and thermodynamic properties portray reliable ionic and transport properties of the solid electrolyte; The average transport number for Mg2+-cations in MgHf4P6O24 solid electrolyte measured as a function of Mg concentration in molten Al is 0.84±0.03. Ionic conductivity and thermodynamic stability of the solid electrolyte in this study was compared to those of MgZr4P6O24 electrolyte [1, 3], which shows novel improvement in the ionic conductivity and thermodynamic properties of both solid oxide electrolytes.Relying on the structural, thermodynamic stability and ionic conductivity data in this study, Mg-sensor probes were designed and fabricated, then tested in molten Al at 700±5oC, using the electrochemical method illustrated in Figure 1[3]. In application, a high-temperature Mg-sensor probe was fabricated using the Mg2+-cation conductors characterised in this study by incorporating a biphasic powder mixture of MgCr2O4+Cr2O3 ceramic reference electrode in air, showing promising trend after successfully sensing Mg dissolved in molten Al alloys at 700±5oC. A linear dependence of sensor voltage on the logarithm of Mg concentration was obtained. The thermodynamic activity of Mg in molten Al shows a rather negative deviation from Raoult's law [4]. MgHf4P6O24 solid electrolyte has useful potential applications in high-temperature Mg-sensors during refining, virgin metals alloying and scrap metal recycling for improved environmental sustainability and climate change. Figure 1. A schematic of high-temperature Mg-sensor test rig [3].

Effect of Al2O3 coating thickness on microstructural characterization and mechanical properties of continuous carbon fiber reinforced aluminum matrix composites

Continuous carbon fiber (CF) reinforced aluminum (Al) matrix composites have become a potential lightweight material in aerospace and commercial applications. In this work, the alumina (Al2O3) coating was uniformly synthesized on the surface of CF by the sol-gel method for improving the wettability and reducing the interfacial reaction between molten Al alloy and CF, while the Al2O3-coated CF was subsequently used to fabricate CF/Al composites via pressure infiltration technique. Effects of heat treatment temperature, immersion time, and immersion-drying cycle on the surface morphologies and mechanical properties of Al2O3-coated CF were studied, and the influences of the coating thickness on the infiltration quality and the mechanical properties of composites were also investigated by means of the microstructural analysis, interfacial characterizations and tensile property tests. The results show that the Al2O3-coated CF with excellent integrity and mechanical properties was obtained at 500 °C for 2 immersion-drying cycles by the immersion time of 5 min per cycle. The Al2O3 coating can effectively improve pressure infiltration quality and mechanical properties based on the suitable interfacial bonding strength and good wettability. The optimized Al2O3 coating thickness is 100 nm for better improving the mechanical properties of CF/Al composites.

Assessment of MgHf4P6O24 Electroceramic Oxide Electrolyte in High-Temperature Electrochemical Sensor for Sensing Mg in Non-Ferrous Alloys

The chemical synthesis of MgHf4P6O24 multicomponent nanostructured ceramic oxide electrolyte was achieved using a modified sol-gel chemical process by substituting the tetravalent Zr4+ B-site in MgZr4P6O24 solid-state electrolyte [1, 2] with tetravalent Hf4+ ceramic oxide resulting in a considerably low activation energy (Ea = 0.74 ± 0.04 eV), promising ionic conductivity (4.52 x 10-4 Scm-1 at 747oC), electroceramic MgHf4P6O24 solid-state electrolyte.MgHf4P6O24 solid-state electroceramic oxide electrolyte was calcined at a relatively low temperature range of 800-900oC, the calcined nanopowders were pressed into pellets of 13mm diameter (Ø) and 3.8mm thickness with a uniaxial steel die at 5kN compressive pressure and sintered at 1000 ≤ T/oC ≤ 1550 temperature range. However, 1300oC was adopted as the sintering temperature in this study haven achieved optimum density and stable sample composition at that temperature. X-ray diffraction reveals a good crystallinity of the electroceramic oxide with an average crystallite size of 20±2 nm and 42±2 nm at 800oC and 900oC, respectively, indicating that crystallite size increases as a function of calcination temperature, which is very consistent with the simultaneous TGA-DSC thermal analysis profiles and confirmed using HR-TEM. The refined crystallographic data and ionic conductivity properties of the novel MgHf4P6O24 ceramic oxide solid-state electrolyte was reported for the first time in this study. SEM-EDS characterisation technique was used for determining both structural and compositional homogeneity. The sintered MgHf4P6O24 electroceramic oxide electrolyte was characterised for their electrical and thermodynamic properties thereby identifying reliable ionic and transport properties of the electroceramic oxide; The average transport number for Mg2+-cations in MgHf4P6O24 electroceramic oxide electrolyte measured as a function of Mg concentration in molten Al is 0.84±0.03. The ionic conductivity and thermodynamic analysis of the novel solid-state electroceramic oxide electrolyte in this study was compared with those of MgZr4P6O24 electrolyte [3], showing novel improvement in the trend of the ionic conductivity and thermodynamic properties of both electroceramic oxide electrolytes.Relying on the structural, chemical stability and ionic conductivity data characterised in this study, solid-state electrochemical Mg-sensor was designed and fabricated, then testing of the high-temperature Mg-sensor in molten Al alloys by the electrochemical method was achieved as shown in Figure 1 [3]. The novel high-temperature solid-state Mg-sensor was fabricated using the novel high conducting Mg2+-cation solid-state electroceramic oxide electrolyte characterised in this study by incorporating a biphasic powder mixture of MgCr2O4+Cr2O3 solid-state ceramic reference electrode in air, showing promising trend after successfully sensing Mg dissolved in molten Al alloys at 700±5oC. A linear dependence of sensor voltage on the logarithm of Mg concentration was obtained. The thermodynamic activity of Mg in molten Al alloy shows a rather negative deviation from Raoult's law. Solid-state MgHf4P6O24 electroceramic oxide electrolyte has useful potential applications in solid-state Mg-sensors during refining, virgin metals alloying and scrap metal recycling for the benefit of our environment and depleting climate.

Influence of TiO2 dopant on spontaneous infiltration to fabricate high volume fraction SiCp/Al cermets

The influence of particulate TiO2 dopant on the rate of spontaneous infiltration into SiC preforms by molten Al alloys and the characteristics of the prepared SiC–Al cermet were investigated qualitatively. To examine the effectiveness of the TiO2 dopant as an infiltration aid, spontaneous infiltration experiments were carried out at different temperatures for preforms doped with TiO2 and for preforms without dopant. Results showed that TiO2 enhances the spontaneous infiltration rate at each temperature level. Via metallurgical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and differential scanning calorimetry (DSC), the characteristics of the cermets produced at different process parameters were examined. The relevant reaction processes between TiO2 and Al and the experimental results are discussed.

Numerical simulation of ultrasonic field within the large-scale Al alloy melts treated by scalable sonotrodes

The single sonotrode-generated ultrasonic field cannot fully spread the whole volume of large-scale Al alloy melt. Then, the effective volume of Al alloy melt processed by ultrasound is very limited. Thus, single sonotrode does not completely satisfy the casting of large-scale Al alloys. Scalable power ultrasounds provide an alternative way for this dilemma. However, only the optimal configuration of scalable power ultrasounds lead to a high efficiency during casting. In the present work, numerical simulation of ultrasonic field within the large-scale Al alloy melts was carried out for three cases, i.e. single sonotrode, three parallel sonotrodes, and three non-parallel sonotrodes that were configured in various ways. Simulation work mainly focused on investigating (a) the three dimensional (3D) distribution of acoustic pressure under different configurations, (b) the 2D distribution of acoustic pressure along each sonotrode’s axis, (c) the 1D distribution of acoustic pressure along the central axis of large-scale Al alloy melts, and (d) the mean acoustic energy density and the cavitation zones as well. Meanwhile, the 3D dynamic evolution of acoustic pressure fields for different configurations was also analyzed in one cyclic vibration time. Compared with single sonotrode, three scalable sonotrodes (when configured in an appropriate way) enable to generate larger high-pressure zones, increase the mean acoustic energy density, and enlarge the volume fraction of potential cavitation zones. The present work raises insights for the configuration and optimization of scalable sonotrodes for casting the large-scale metallic materials, like Al alloy.

Preparation and Properties of Fused Zircon

Melting of zircon with added glass-forming oxides is reported. The structures of the synthesized materials were baddeleyite and a glassy phase, which determined the operating characteristics of the refractory. Corrosion tests of fused zircon samples in Al-alloy melts showed that they were not wetted and minimally corroded. Treatment of fused zircon with HF solution (10%) produced a material with <2% SiO2. The silica content in the fused zircon decreased by three times with carbothermic melting in an electric arc furnace.

A CALPHAD (CALculation of PHAse Diagrams)-based viscosity model for Al-Ni-Fe-Co melt system

In this paper, a CALPHAD (CALculation of PHAse Diagram)-based viscosity model has been established for multicomponent liquid systems, using Al-Ni-Fe-Co melt as an example. Firstly, the viscosity databases of pure Fe and Co liquids were assessed following an Arrhenius equation based on the available experimental viscosity data. The viscosity databases of pure Ni and Al liquids were adopted from our previous research and literature. Subsequently, viscosity databases of the Al-Fe, Al-Co, Fe-Co, Fe-Ni, Co-Ni binary liquids were assessed using the CALPHAD model and compared with the available experimental viscosity data. For the first time, the temperature- and composition-dependent binary interaction parameters were used to describe the non-linear viscous behavior due to the chemical short-range order. The viscosities of ternary Al-Fe-Ni liquid were predicted from the databases directly extrapolated from sub-binary systems using the Redlish-Kister-Muggianu model. The good agreement of viscosity between present calculations and available experiments in Al alloy melts demonstrated that the CALPHAD-based viscosity model is suitable for predicting the viscosity of multicomponent liquids as well as their complex temperature-composition-phase-viscosity relationships.