The structural reliability of pistons operating under severe thermo-mechanical loading strongly depends on the properties of the selected Al–Si alloy. This study presents an integrated experimental–numerical investigation of hypereutectic Al–Si alloys intended for piston applications. Phase constitution and silicon morphology were characterized by metallography and X-ray diffraction, while tensile testing provided mechanical properties for finite element modeling. The experimentally determined parameters were implemented in a three-dimensional piston model to evaluate stress distribution, deformation, and safety margins under maximum combustion pressure and maximum engine speed. The simulations revealed maximum von Mises stresses up to 150 MPa, with inter-alloy differences below 0.3%, indicating geometry-dominated stress behavior. The maximum displacement did not exceed 76 µm, varying by approximately 3% between alloys. In contrast, the minimum factor of safety ranged from 1.20 to 1.35, showing differences of up to 12%, primarily governed by yield strength and microstructural homogeneity. The results demonstrate that piston performance under combustion-dominated loading is strength-controlled rather than stiffness-controlled. The study provides quantitative insight into the structure–properties–performance relationship of hypereutectic Al–Si alloys and supports informed material selection for preliminary piston design.

The present study examines the influence of plastic deformation on the corrosion behavior of aluminum alloy EN AW-2024 (AlCu₄Mg) in an acidic medium (0.5 M H₂SO₄). Specimens without deformation and with a degree of plastic deformation of 25%, 33% and 50% were studied. Corrosion tests were carried out using the gravimetric method for a period of 72 h. The inhibitory effect of environmental inhibitors—ascorbic acid (vitamin C) and citric acid—was also evaluated. The results show that the degree of plastic deformation has a significant influence on the corrosion rate of the studied alloy. The lowest corrosion rate is observed at 25% deformation, while at higher degrees, the resistance decreases. It was found that citric acid exhibits the highest inhibitory effect at 33% deformation (77.27%), while vitamin C shows a better effect at 50% deformation. The results obtained show that the optimal degree of deformation in combination with a suitable inhibitor can significantly improve the corrosion resistance of EN AW-2024 alloy in acidic environments.

In this work, a non-standardized hypereutectic aluminum–silicon alloy AlSi21Cu5MgCr intended for the automotive industry is presented. The modification of the alloy is performed with the conventional modifier phosphorus in an amount of 0.04 wt%. The applied metallurgical treatment is the basis for the obtained modified structure. It has been established that after conducting the T6 heat treatment, the free silicon crystals are reduced to 26.9 µm, and the eutectic silicon crystals are spherical in shape and have dimensions not exceeding 8 µm. The macrohardness of the studied alloy is 168.5HV_10/10, a value significantly higher than that required for this type of alloy, which is in the range of 95 ÷ 137 HV (90 ÷ 130 HB). The microhardness of the α-phase in the composition of the eutectic is 154 µHV_50/10, which indicates that after quenching a saturated solid solution was fixed, and during the artificial aging process secondary strengthening phases were formed and separated. A CrAlN hard coating was deposited on the alloy surface. The mechanical properties of the coating were characterized by a hardness of 14 GPa, whereas the AlSi21Cu5MgCr substrate had a hardness of 2 GPa. The results showed considerable improvement of the hardness of the new alloy and well-tuned elastic–plastic properties. The obtained adhesive properties are compatible with this class of materials. The composition of the CrAlN hard coating is homogeneously distributed on the alloy surface and the morphology is improved. The investigations showed that CrAlN hard coatings could successfully be applied for the modification of the surface of AlSIMgCu alloys.

The present study investigates the surface modification of tool steel 1.2343 (EN ISO 4957) by ion nitriding. Prior to the chemical–thermal treatment, the specimens were subjected to heat treatment consisting of vacuum quenching followed by triple tempering, ensuring structural stabilization before the diffusion process. Ion nitriding was carried out under two temperature–time regimes, namely 490°C for 16 h and 500°C for 11 h, in order to evaluate their influence on microstructure, hardness distribution, and tribological behaviour. Microstructural analysis revealed the absence of a compound (white) layer composed of ε and γ′ phases, while a diffusion layer with a relatively uniform thickness of up to ~250 µm was observed. The effect of the nitriding parameters on surface hardness and hardness depth profiles—from the surface to the core—was systematically analyzed. In addition, tribological tests were performed to determine the coefficient of friction and wear characteristics of the treated surfaces. The results indicate that the applied nitriding regimes significantly influence the development of the diffusion layer and the surface properties, with the regime at 500°C providing a more favorable balance between hardness and tribological performance.