Oxide bifilms are increasingly recognised as the dominant defects governing the quality and performance of cast aluminium alloys. However, conventional Reduced Pressure Testing (RPT) only detects bifilms that inflate during solidification, thereby underestimating the true bifilm population. This study develops a theoretical framework to quantify bifilm generation during two critical melt-treatment operations: melt transfer and rotary degassing. Models based on Weber-number-controlled bubble entrainment and breakup were used to estimate bifilm formation rates and characteristic defect sizes. Under typical industrial processing conditions consisting of two melt transfers and rotary degassing, a minimum bifilm concentration of 1,577 mm -3 was predicted, with melt transfer identified as the principal source of defect generation. Experimental assessment of bifilm populations using focused ion beam serial sectioning and three-dimensional reconstruction revealed approximately 187,500 hidden oxide defects mm -3 , exceeding predictions by more than two orders of magnitude. Incorporation of daughter-bubble formation increased the estimated concentration to approximately 6000-8000mm -3 , but a substantial discrepancy remained, indicating that many bifilms likely pre-exist in primary aluminium feedstock. A damage-factor model that combines defect size, numbers, and tensile specimen geometry further demonstrated that melt-transfer operations are considerably more damaging than degassing. Furthermore, degassing becomes more damaging at a certain rotation rate, supporting a change in current rotary degassing practice.

Global aluminium production has been surging in recent years due to its favourable properties, which can be tailored through alloying. To cope with this increasing demand, aluminium production has shifted increasingly towards primary production, as secondary production is restricted by impurity accumulation, particularly iron (Fe). The addition of Fe-bearing intermetallic particle formers, such as manganese (Mn), chromium (Cr), and strontium (Sr), is a potential solution. In contrast to previous studies, which mainly focused on higher-Fe Al-Si alloys, the present work investigates the impact of varying Mn-Cr and Mn-Sr additions on the Fe removal efficiency, defined as the percentage of Fe content in the melt after sedimentation relative to the initial Fe content, the formation of Fe-bearing intermetallic particles and the yield of clean Al following particle sedimentation in low-Fe Al-Si alloys. The experimental work included small-scale melting with 8 kg of Al-11Si-0.5Fe alloys. The study concludes that using Fe-bearing intermetallic particle formers, such as Mn and Cr, is effective for low Fe concentrations in the melt. However, a higher quantity of Mn at constant Cr is necessary for a more efficient reduction of Fe. When comparing Mn-Cr with Mn-Sr additions, Mn-Cr additions improve Fe removal efficiency, whereas Mn-Sr significantly improves the clean aluminium output yield with lower Fe removal efficiency. Further increases in Sr adversely affect particle yield and packing density, with no impact on Fe removal efficiency.

The aluminum casting industry plays a pivotal role in modern manufacturing, contributing to sectors such as automotive, aerospace, and construction. However, the increasing demand for aluminum, coupled with environmental concerns, necessitates a critical evaluation of its raw material sourcing and energy-intensive casting processes. This study explores the dual challenges of raw material criticalities and furnace selection choices in primary and secondary aluminum casting, aiming to chart a pathway toward more sustainable foundry practices. The study is based on the definition of criticality and environmental assessments for a more circular and climate-resilient future. Raw material criticality assessment is assessed through six factors: (1) abundance of elements in the Earth’s crust, (2) sourcing and geopolitical risk, (3) environmental country risk, (4) supply risk, (5) economic importance, and (6) recycling input, while the environmental assessment is made through two major loads: (i) embodied energy, and (ii) carbon footprints. A comparative analysis of common furnace types, including crucible, induction, reverberatory, and stack furnaces, with varying in-house return rates, is conducted to examine the trade-offs in performance from a sustainability perspective. The findings of the proposed work will emphasize the importance of material and process selection in foundries to save the reserves of critical raw materials, implement better closed-loop recycling systems, integrate renewable energy sources, and develop smart furnace operations to minimize environmental footprints. This comprehensive approach is vital for transitioning the foundry industry toward a more circular and climate-resilient future.

The rapid rise of electric vehicles and the adoption of Giga/Mega/Hyper-casting are transforming automotive manufacturing and dramatically increasing the demand for aluminium components. This shift exposes critical challenges in high-pressure die casting (HPDC), particularly the inability to perform fast, in-line quality assessment and the persistent deterioration of melt quality during handling and mould filling. The current state-of the art understanding is that “hydrogen is not the primary issue; air entrainment and oxide bifilm are”. Furthermore, “bifilm generation is dominated by melt handling and mould filling.” These defects fundamentally limit mechanical performance, fatigue life, and crashworthiness. Current mitigation strategies—such as gate segmentation and reduced gate speed—offer only partial improvement. The analysis shows that unstable fill-front behaviour in HPDC inherently promotes bifilm formation, whereas semisolid casting can stabilise the flow, suppress fill-front instabilities, and reduce oxide damage. This creates new opportunities for high-integrity structural castings but also introduces challenges related to slurry rheology and segregation. Overall, the work identifies melt handling, fill-front stability, and real-time quality control as the central barriers to producing defect-free aluminium components for next-generation automotive applications.

Ontologies are essential for structuring domain knowledge, improving accessibility, sharing, and reuse. However, traditional ontology construction relies on manual annotation and conventional natural language processing (NLP) techniques, making the process labour-intensive and costly, especially in specialised fields like casting manufacturing. The rise of Large Language Models (LLMs) offers new possibilities for automating knowledge extraction. This study investigates three LLM-based approaches, including pre-trained LLM-driven method, in-context learning (ICL) method and fine-tuning method to extract terms and relations from domain-specific texts using limited data. We compare their performances and use the best-performing method to build a casting ontology that validated by domian expert.

This study evaluated the friction, wear, and airborne brake wear particle (BWP) emissions of aluminum-based metal matrix composite brake discs fabricated from recycled aluminum alloy reinforced with silicon carbide particles (Al-SiCp MMC). The study further conducted a comparative analysis of the friction, wear, and BWP emissions of Al-SiCp MMCs against those of a commercial gray cast iron (GCI) brake disc, which served as a reference. The results show that the steady-state coefficient of friction for all Al-SiCp MMC brake discs remained consistently between 0.4 and 0.45, within the typical range for brake materials. A clear transfer layer was observed on the surfaces of Al-SiCp MMC discs after testing, resulting in apparently milder wear due to material transfer and reduced BWP emissions. Al-SiCp MMC brake discs resulted in higher wear rates for the mating pins than the GCI discs, with wear rates increasing as the fraction of secondary aluminum in the matrix increased. Within the measurement range of this study, both GCI and Al-SiCp MMC brake discs exhibited monomodal number-weighted particle size distributions in the steady state, with the mode size of approximately 0.5 & micro;m. Future research should employ advanced particle samplers capable of detecting nanosized particles and explore more severe testing conditions, including higher contact pressures, speeds, and temperatures.

Over the past decades, demand for high-purity aluminium (Al) has increased in many sectors, like aerospace and automotive sectors, since it combines a high level of purity with the flexibility of controlled alloying, which allows for tailored enhancements of material properties. To accommodate the rising demand, primary Al production has significantly increased since the refining of secondary Al is constrained by high impurity levels, especially iron (Fe). A way to mitigate this problem is to add Fe-bearing intermetallic particle formers, like manganese (Mn). This paper investigates the influence of different Mn additions for low-Fe composition aluminium melts at a cooling rate of 3 °C/min, as the primary Fe-rich phases may differ and cannot be extrapolated. More specifically, the impact of filters, the Fe removal efficiency for different Mn additions, and the Fe-bearing intermetallic particles’ Fe removal potential. Fe removal potential was evaluated by combining intermetallic particle area fraction with their average Fe content. This was done by running Thermo-Calc equilibrium calculations to guide the planning of the experimental work. Then, running small-scale experiments with 8 kg of Al-11Si-0.5Fe alloy. The study concludes that the Fe-bearing intermetallic parties sedimented at the bottom of the furnace since the composition of the filtered and unfiltered samples from the top part of the melt was similar. Additionally, larger amounts of Mn are required to improve the Fe removal efficiency for low-Fe concentration Al-Si cast alloys since it improves the Fe removal potential and increases the amount of Fe-bearing intermetallic particles in the melt.

Article Room and High-Temperature Wear Behaviour of Al-Based MMCs against an Automotive Brake Pad Lucia Lattanzi * and Anders Eric Wollmar Jarfors Department of Materials and Manufacturing, School of Engineering, Jönköping University, Gjuterigatan 5, 55318 Jönköping, Sweden * Correspondence: lucia.lattanzi@ju.se Received: 29 November 2024; Revised: 27 December 2024; Accepted: 31 December 2024; Published: 6 January 2025 Abstract: Aluminium metal matrix composites are promising materials for automotive brake discs, and it is critical to assess their wear performance in different braking conditions. This article presents the wear behaviour of aluminium-based composites with different Al-Si matrix alloys added with nickel and copper to retain mechanical strength at high temperatures. The wear tests were conducted at room and high temperatures (250 and 400 °C) to simulate different braking conditions on a pin-on-plate tribometer. The coefficient of friction is in the range of 0.15–0.17 for all materials at room temperature. The specific wear rates of the brake pad and the disc materials indicate that material transfer occurs from the brake pad to the metal counterpart. Microscopy investigations of the wear tracks confirm the material transfer on the composites. It protects the composite surface from wear damage and maintains a stable coefficient of friction. To translate these results into real-world scenarios, the findings of this study suggest that aluminium-based metal matrix composite brake discs have a longer product lifespan compared to the grey cast iron brake discs; the brake pads for the composites would be the components to need replacement due to wear during the product life instead of the brake discs.

The shift towards vehicle electrification must progress while simultaneously addressing sustainability challenges related to lightweighting, which is the intensifying need for high-quality primary aluminium, which demand cannot be met with recycled material with traditional compositional limits. To understand and predict the characteristics of future scrap mixtures, it is crucial to comprehend the evolving composition of new components and associated trends. This insight helps alloy design that accommodates higher impurities and, thus, a more thoughtful strategy for materials process development research. This review delves into the impact of electric motors, batteries, and functional integration. Notably, the analysis herein indicates a rise in magnesium (Mg) and a decrease in copper (Cu) and silicon (Si) contents in the future scrap mixtures due to more Al-Mg alloys such as those found in the 5xxx (Al-Mg) and 6xxx (Al-Mg-Si) series and an outflux of high Al-Si-Cu engine alloys. Gigacastings might counteract this trend based on their Si content and adoption and promote circularity principles by reducing alloy varieties. Reduced Si content in future scrap mixtures is also expected to boost sustainability since significant CO2 emissions from recycled alloys come from melting, controlled by the latent heat of fusion of the scrap mix.

The shift towards vehicle electrification must progress while simultaneously addressing sustainability challenges related to lightweighting, which is the intensifying need for high-quality primary aluminium, which demand cannot be met with recycled material with traditional compositional limits. To understand and predict the characteristics of future scrap mixtures, it is crucial to comprehend the evolving composition of new components and associated trends. This insight helps alloy design that accommodates higher impurities and, thus, a more thoughtful strategy for materials process development research. This review delves into the impact of electric motors, batteries, and functional integration. Notably, the analysis herein indicates a rise in magnesium (Mg) and a decrease in copper (Cu) and silicon (Si) contents in the future scrap mixtures due to more Al–Mg alloys such as those found in the 5xxx (Al–Mg) and 6xxx (Al–Mg–Si) series and an outflux of high Al–Si–Cu engine alloys. Gigacastings might counteract this trend based on their Si content and adoption and promote circularity principles by reducing alloy varieties. Reduced Si content in future scrap mixtures is also expected to boost sustainability since significant CO2 emissions from recycled alloys come from melting, controlled by the latent heat of fusion of the scrap mix.

Electrification is a keyword for many industries today, and thermal management is essential. This paper aims to review the sustainability perspective and analyse the need for thermal conductivity. A model for thermal conductivity is developed for as-cast and heat-treated states to be used as a basis for a sustainability impact index to allow quantitative decisions on sustainable alloying for heat transfer solution alloy development and selection. In the analysis, it was necessary to consider microstructural features for a satisfactory description of the thermal conductivity measured from a set of Al-Si-based alloys in the as-cast and heat-treated states. An environmental impact index was developed for the alloying elements to gauge the effectiveness of different alloying elements, including the environmental impact. An effort to include the microstructural effects was made. Due to the low thermal conductivity of the matrix phase in the as-cast state, the eutectic regions provide a positive contribution to the correction factor developed. The heat-treated stat microstructure seems to lack importance in the ranges of Si additions used in the current study.

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.

To satisfy the rising demand for higher product quality and giga-casting requirements, the casting process is undergoing significant changes. However, current control methods rely significantly on human expertise and experience, making process availability and stability difficult to ensure. The semisolid casting process is more complicated than conventional liquid casting due to the additional casting parameters incorporated during the slurry preparation, which can have an effect on the quality of the final product. Therefore, an efficient tool is required to simplify the complete process of semisolid casting. The introduction of an AI system to aid in the supervision of the casting manufacturing procedure is one potential solution. This paper introduces a new casting system named ”Smart-Cast” developed for this specific purpose. The paper describes the functions of the system and its current development process. Using an AI system as an assistant can help to achieve the goal of enhancing the efficacy of casting process control, and it can also help foundries step into the Industry 4.0 era.

Aluminum-based composites provide tribological performance and thermophysical properties that, combined with being lightweight, are suitable for their application in automotive brake discs. Aluminum alloys allow the use of secondary materials to produce composites, with the drawback of several elements, impurities, and oxides that can harm the mechanical and thermophysical properties. This preliminary study explored the mechanical and thermophysical performance of a composite material produced with a secondary matrix alloy. Overall, the results are promising, with a minimal decrease in mechanical and thermophysical properties despite clustered silicon carbide particles in the composite with the secondary matrix. The challenges in effectively dispersing carbides in the melt seem linked to aluminum oxides, and future microstructural investigations will aim to clarify this aspect.

In this study, the in situ 4 wt.% TiB2(p)/Al-Cu composite was prepared through a mixed salt reaction method. To evaluate its formability, hot isothermal compression tests were performed using a Gleeble-3500 system in a temperature range of 480-510 degrees C and a strain rate range of 0.1-10 s(-1). A constitutive model of the composites with strain compensation was established, and the true stress-strain curves revealed that the composite exhibited favorable formability at 510 degrees C. Additionally, single-pass equal channel angular pressing (ECAP) processes were conducted at room temperature and 510 degrees C to investigate the microstructure evolution of the composite. The distribution of TiB2 particles was found to be influenced by deformation temperature, while the microstructural characteristics of the aluminum matrix were minimally affected. Furthermore, a comparison between the as-cast composite and the deformed composites revealed the presence of different preferred orientations in the two conditions, and the corresponding paths of texture evolution were estimated accordingly. Remarkably, after undergoing single-pass ECAP, the Schmid factors of composites remained nearly unchanged, demonstrating that deformed composites were still appropriate for processing and as such demonstrating a potential route also for formability assessment.

Bifilms have been proposed to be critical for forming casting defects. The reduced pressure test (RPT) and bifilm index (BI) have been widely studied and used in industry for melt quality assessment. However, the BI remains challenged in predicting the mechanical properties. This work investigated the usage of RPT for elongation prediction by analyzing the melt in two foundries. The results showed that the BI could be valid when the bifilms exist as fully inflated pores. In reality, bifilms present as pores with various morphology and distribution, generating local stress concentrations under tension. Consequently, the parameter areaeff, which considers the pores’ morphology and distribution, was proposed, and the resultant f eff showed a good correlation with the elongation of the castings. These results guide the foundry to predict the elongation of the final castings and give directions for further research on the bifilm defects.

A new simple approach was developed to assess the Complete Melt Quality of aluminium cast alloys throughout the production line. The approach relies on the concurrent use of reduced pressure tests (RPT) and tensile tests at each station in the production line when the melt is transferred and/or processed. These tests can be used to determine the source of melt-related problems in the production line. Two case studies from the procedure of both an aluminium die-casting and a rheo-casting plant showed that melts were significantly damaged in the tower furnace and got progressively more damaged through the production line proven by the RPT, tensile test, and fracture surface analysis results.

The objective of the present study is to evaluate the hot tearing tendency based on the Clyne and Davies model by evaluating the critical times which can be obtained using a newly developed method. A method to determine the critical times required to calculate the crack susceptibility was presented based on the measurement results with Al–Si alloys, and the method to calculate the crack susceptibility coefficient was presented. In the newly developed method named “Signal intensity method,” signals were generated by tapping the edge of a waveguide which is immersed in molten and solidifying sample and the critical solid fractions were obtained from the signal intensity change. The conventional thermal analysis was also performed simultaneously and the corresponding critical points were identified. The method shown in the present study will enable the determination of the crack susceptibility coefficient with higher accuracy.

Semisolid processing can provide an avenue to reduced rejection rates during casting and increased capability of thin-walled castings leading to improved resource efficiency and reduced climate impact. In the RheoMetal TM process, the slurry is formed far from equilibrium. A consequence to the deviation from equilibrium is that conventional guidelines for process stability may not give the correct appreciation of the process window, nor on the correct solid fractions generated. The solid fraction provides the slurry properties and its dependence on temperature should in theory provide the stable process window. This is discussed using data from literature and an alternative approach to identify the process stability window is given.

High-pressure die-casting (HPDC) can be a productive process for high-quality cast aluminium alloy components. However, it is also a process prone to generate defects, such as gas porosities and incomplete fillings, resulting in rejections. One way to reduce the reject rate is to employ Semi-Solid Metal processing with HPDC. The most important advantages of Semi-Solid alloys are reduced shrinkage defects, fewer gas porosities, and fewer chances of filling-related problems. To take full advantage of a semi-solid metal slurry, the casting process must be controlled meticulously to reach homogeneous casting quality and high process repeatability. A study has been conducted on cast parts composed of two-dimensional symmetrical cavities. From the mechanical tests, unexpected differences emerged in both tensile strength and fracture elongation, which were confirmed by differences in the microstructure. The paper investigates the reasons for the asymmetry in the proprieties to avoid similar problems in future studies and maximize the effectiveness and repeatability of the high-pressure die-casting process.