RHEINFELDEN CASTASIL-37

Rheinfelden Castasil-37 (AlSi9MnMoZr) is an aluminum-silicon-manganese-molybdenum-zirconium high pressure die casting (HPDC) alloy. It was developed by Rheinfelden Alloys GmbH for the production of large and complex high pressure die castings for automotive structural applications. This alloy is used in the as-cast condition, and exhibits good mechanical properties, especially elongation, which are superior to those of conventional aluminum-silicon alloys. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as casting, heat treating, and joining. Filing Code: Al-481. Producer or source: Rheinfelden Alloys GmbH & Co. KG.

INVESTIGATION OF THE INFLUENCE OF THE MODIFIERS P, SR, TI AND COMBINATIONS OF THEM ON THE STRUCTURE AND MECHANICAL PROPERTIES OF ALSI25 ALLOY

The most commonly used elements to modify primary silicon crystals in the structure of hypereutectic aluminum-silicon alloys are phosphorus and sulfur. Phosphorus has been shown to have the highest coefficient of modification with respect to the primary silicon and is therefore a preferred modifier. There are also data on the positive effect of the modifiers Sb, Sr, Ti, and B on the silicon crystals in the structure of this type of alloys. The influence of the modifiers phosphorus, strontium, titanium and combinations of them on the size and shape of both the primary silicon crystals and the silicon crystals in the composition of the eutectic of the AlSi25 alloy has been studied in this work. Mechanical tests have been performed to determine both the strength and the plastic parameters of the investigated alloy (in unmodified and modified state). The classic for this type of alloys modifier - phosphorus - has been introduced into the melt by the ligature CuP10. Strontium has been introduced by the ligature AlSr10, and titanium - by the ligature AlTi5B1, the two ligatures in the form of rods. The investigated alloy has also been modified by combinations of the used modifiers: phosphorus and strontium, phosphorus and titanium.The influence of the used modifiers on the structure and mechanical properties of AlSi25 alloy has been discussed.

INVESTIGATION OF THE INFLUENCE OF DIFFERENT MODIFIERS ON THE EUTECTIC SI IN THE COMPOSITION OF ALSI18 ALLOY

The structure of hypereutectic aluminum-silicon alloys consists of primary silicon crystals arranged in a eutectic matrix. In the present work the influence of different types of modifiers on the size and shape of the silicon crystals in the composition of the eutectic of the AlSi18 alloy has been studied. The classic for this type of alloys modifier (phosphorus), as well as the nanomodifiers SiC and nanodiamonds (ND) have been used. The results of the microstructural analysis show that the three modifiers used affect differently the shape and size of the eutectic silicon of the investigated alloy.

Defects, Diffusion and Dopants in Sillimanite

Aluminum silicate based mineral “Sillimanite” (Al2SiO5) is important in the industrial preparation of aluminum-silicon alloys and cement. In the present study classical pair potential simulations are used to examine the intrinsic defect processes, diffusion pathways of Al3+ and O2− ions together with their activation energies and promising dopants on the Al and Si sites in Al2SiO5. The cation anti-site (Al-Si) defect cluster is calculated to be the most favorable defect, highlighting the cation disorder in this material, in agreement with the experiment. The cation disorder is important as this defect can change the mechanical and chemical properties of Al2SiO5. The Al3+ ions and O2− ions migrate in the c direction with corresponding activation energies of 2.26 eV and 2.75 eV inferring slow ion diffusion. The prominent isovalent dopants on the Al and Si sites are found to be the Ga and Ge, respectively, suggesting that they can be used to prevent phase transformation and tune the properties of sillimanite.

Fracture–Mechanical Assessment of the Effect of Defects on the Fatigue Lifetime and Limit in Cast and Additively Manufactured Aluminum–Silicon Alloys from HCF to VHCF Regime

Aluminum–silicon alloys are commonly used in die-cast and additively manufactured (AM) light-weight components due to their good processability and high strength-to-weight ratio. As both processing routes lead to the formation of defects such as gas and shrinkage porosity, a defect-sensitive design of components is necessary for safe application. This study deals with the fatigue and crack propagation behavior of die-cast alloy AlSi7Mg0.3 and additively manufactured alloy AlSi12 and its relation to process-induced defects. The different porosities result in significant changes in the fatigue stress-lifetime (S–N) curves. Therefore, the local stress intensity factors of crack-initiating defects were determined in the high and very high cycle fatigue regime according to the fracture mechanics approach of Murakami. Through correlation with fatigue lifetime, the relationship of stress intensity factor (SIF) and fatigue lifetime (N) could be described by one power law (SIF–N curve) for all porosities. The relationship between fatigue limit and defect size was further investigated by Kitagawa–Takahashi (KT) diagrams. By using El Haddad’s intrinsic crack length, reliable differentiation between fracture and run out of the cast and AM aluminum alloys could be realized. SIF–N curves and KT diagrams enable a reliable fatigue design of cast and AM aluminum alloys for a finite and infinite lifetime.