Author: Alice Siemund, TRIMET Aluminium SE
Published online: February 23, 2026 (conference paper)
Summary: The study examines the naturally hard die-casting alloy trimal-38 (type AlSi8ZnMn), developed for structural components in the automotive sector. It assesses whether a secondary-based version with elevated levels of the critical elements iron (0.35 wt%) and copper (0.15 wt%) can meet the same requirements. Building on earlier lab-scale gravity casting trials, the process was scaled up to high pressure die casting to test how well the findings transfer. Mechanical performance was characterized through tensile testing and complementary plate bending tests, supported by thermodynamic calculations and microstructural analysis. The work identifies suitable iron and copper concentration ranges and evaluates their effect on microstructure, mechanical properties, and the alloy's suitability for recycling-based production.

Author: Dr. Roman Düssel, TRIMET Aluminium SE
Published online: February 23, 2026 (conference paper)
Summary: Calcium enters primary aluminum production through the raw materials, causing the concentration of calcium fluoride in the bath to fluctuate over time. The paper focuses on the pathways by which calcium enters and leaves the process, as well as its recirculation routes. Drawing on operational data from TRIMET Aluminium SE, the study quantifies calcium enrichment factors and discusses the implications for bath chemistry control. It outlines both the positive and negative effects of CaF₂ on bath properties and presents strategies for managing calcium content.

Author: Tobias Beyer, TRIMET Aluminium SE
Published online: February 3, 2024 (conference paper)
Summary: Producing aluminum alloys from end-of-life (EoL) scrap brings increased levels of iron, copper, and zinc. The paper evaluates the influence of these elements with particular emphasis on phase formation, applying CALPHAD methods to three questions: whether a defined heat treatment can compensate for the formation of Al9Si2Fe2 and Al2Cu, how combinations of these elements affect the formation of detrimental phases, and whether a combined approach of heat treatment and alloy design holds up for higher amounts of Fe, Cu, and Zn in primary-based alloys. The results show that copper and zinc, up to the limits established in common supply specifications, are less detrimental to alloy properties. Iron proved manageable, in good agreement with previous findings.

Author: Alice Siemund, TRIMET Aluminium SE
Published online: February 3, 2024 (conference paper)
Summary: Recycled Al-Si cast alloys with rising levels of contaminating elements are prone to forming certain secondary phases, particularly under slow solidification. This calls for a solid understanding of how typical recycling impurities such as iron and copper affect the resulting alloy's microstructure and mechanical properties. For the alloy AlSi8ZnMn, the paper investigates and discusses three questions: Does CALPHAD calculation predict the presence of detrimental phases in the model recycling cast alloy studied here? Do the mechanical properties deviate from primary-based alloys? And can the findings from the practical experiments be correlated with the CALPHAD results? The results show that copper, often cited as detrimental in cast alloys, can be used across a higher concentration range than expected, while the influence of iron proved to be more critical.

Author: Andrey Yasinskiy, TRIMET Aluminium SE
Published online: February 3, 2024 (conference paper)
Summary: Metallic anodes enable oxygen evolution during aluminum reduction in electrolysis cells with vertical electrodes. Although considered non-consumable compared with carbon anodes, they tend to corrode in molten fluoride media, and the corrosion products end up in the 
aluminum as impurities. The major challenge for the industry is identifying the conditions (anode and bath composition, temperature, and current density) that yield the lowest corrosion rate. The most reliable way to characterize the corrosion rate is to run an electrolysis test and determine the mass of anode components in the produced aluminum, but this method is highly time- and resource-intensive. The paper investigates the link between the electrochemical parameters of the anode process, which can be measured within minutes, and the results of long-term electrolysis tests. Several parameters, such as exchange current density on clean and oxidized surfaces, were studied in the low-temperature KF-NaF-AlF3-Al2O3 melt at 800 °C. A linear dependency between exchange currents and corrosion rate was found.

Author: Tobias Beyer, TRIMET Aluminium SE
Published online: February 9, 2023 (conference paper)
Summary: Producing aluminum alloys from end-of-life (EoL) scrap brings increased copper and iron contents, since these elements cannot be removed economically from the melt. In this work, Cu- and Fe-containing variants of the alloy AlSi7Mg0.3 were produced at laboratory scale using gravity die casting, based on CALPHAD simulations. Microstructural analyses and tensile tests in the as-cast state were carried out to characterize the influence of copper and iron on microstructure and mechanical properties. The results show that iron and copper contents above the known limits of the standards can still yield good mechanical properties. Hardness, yield strength, and tensile strength correspond well to those of the base alloy, with only minor losses in elongation.