In the present study, wear behavior as a function of aging time was evaluated for the AlCoCrFeNi_2.1 eutectic complex, concentrated alloy (CCA) consisting of B2 (BCC), and L1₂ (FCC) lamellae in the as-cast state. By aging the material at 800 °C up to 500 h, precipitation of a fine, evenly dispersed micro-phase inside the L1₂ takes place. From 500 h to 1000 h of aging, precipitates coarsen by the Ostwald ripening mechanism. Reciprocating wear tests were characterized by a prevailing abrasive wear mechanism, while adhesive and delamination wear components change with aging conditions. The L1₂ phase with lower hardness in the as-cast material preferentially deformed during the wear test, which was not the case after aging the material, i.e., with the presence of precipitates. Aging-induced changes show a similar trend for the coefficient of friction and L1₂ + precipitates phase fraction, whereas changes in specific wear rate are in a good agreement with changes in B2 phase fraction. In general, aging the AlCoCrFeNi_2.1 CCA at 800 °C up to 500 h decreases its coefficient of friction due to reduced adhesive wear component and enhances its wear performance through precipitation strengthening.

In recent decades, considerable efforts have been made in the production of steel and the modification of its microstructure on the nano-scale in order to improve its mechanical properties. One possibility is through nano-particles incorporation and reinforcement. While typical production methods for Metal Matrix nano-Composites (MMnCs) are difficult and expensive, the main drawback of the casting method is the agglomeration of the nano-particles and a poor interface between the nano-particles and the metal matrix. Therefore, the aim of this study was to investigate the potential of adding nano-particles as reinforcement elements through the conventional liquid-metal casting process. The investigation was focused on the various approaches to the modification and addition of nano-particles in the melt, as well as the influence of particle concentration and size on their homogeneity and distribution within the steel matrix. The results show that also in the case of the conventional casting process, it is possible to produce a reinforced steel-matrix nano-composite with a homogeneous distribution of the Al₂O₃ nano-particles in the matrix. However, in order to obtain a homogeneous distribution of nano-particles in the steel matrix, a dispersion agent is required.

The aim of the study was to assess the influence of adding Al2O3 nano-particles of 0.5 wt. % with the mean particle size of 500 nm on the mechanical properties and wear behaviour of the austenitic stainless steel matrix reinforced with nano-particles produced by conventional ingot casting. The focus was on the methods and possibilities of homogeneous and uniform distribution of the particles within the steel matrix using conventional casting routes. The main drawback of the casting method used is the agglomeration of the particles and poor interface between the particles and the metal matrix. The results show that through a proper insertion method, nano-particles can be successfully introduced into the metal matrix. The Al2O3 nano-particles were successfully incorporated into the steel matrix with no signs of clustering and intermetallic reactions taking place between the nano-particles and the steel matrix. This led to improved mechanical properties as well as the wear behaviour of the stainless steel, achieved by using conventional casting routes.

Purpose: This study aims to focus on the development of an experimental setup for testing tribological pairings under a gas atmosphere at pressures up to 10 bar. Design/methodology/approach: A pressure chamber allowing oscillating movement through an outer shaft was constructed and mounted on an oscillating tribometer. Due to a metal spring bellows system, a methodology for the evaluation of the coefficient of friction values separately from the spring forces was developed. Findings: The selected material concept was qualitatively and quantitatively assessed. An evaluation of the static and the dynamic coefficient of friction was performed, which was crucial for the understanding of the adhesion effects of the tested material pairing. The amount of information that is lost due to averaging the measured friction values is higher than one would expect. Originality/value: The developed experimental setup is unique and, compared with the existing tribometers for testing under gas ambient pressures, allows testing under contact conditions that are closer to real applications, such as compressors and expanders. An in-depth observation of the adhesion and stick–slip effects of the tested material pairings is possible as well. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2023-0173/