The study of wear resistance of composite materials is a key aspect in the development of new, more durable structural materials. In this study, the subject of analysis is composite surface layers based on Al–6Mg alloy, reinforced with quasicrystalline AlCuFe particles. The aim of the work is to establish the relationship between the size of the reinforcing particles, the microstructure of the resulting composite, its hardness and, as a result, wear resistance.
To create composite layers, the method [specify the method of application, for example, laser cladding or plasma spraying] was used, which allows the introduction of AlCuFe particles of various sizes (from [specify the minimum size] to [specify the maximum size] micrometers) into the surface layer of the Al–6Mg alloy. The microstructure of the obtained layers was studied using optical and electron microscopy, which made it possible to evaluate the uniformity of the distribution of AlCuFe particles in the matrix, as well as the presence of defects (pores, cracks) in the composite structure.
Alloys reinforced with ceramic, intermetallic or quasicrystalline elements can meet the high demands of the automotive and aerospace industries due to their outstanding properties. In this work, the surface layers of Al–6Mg alloy samples were modified by ultrasonic impact treatment (UIT). This process induces mechanical mixing of the matrix with quasicrystalline (QC) particles of AlCu25Fe12 embedded in the zone of severe plastic deformation.
The wear resistance and friction of both the original alloy and the alloy reinforced with QC particles were investigated under quasi-static and dynamic conditions. Particular attention was paid to the influence of the QC particle size and the type of testing on the wear resistance and microhardness of subsurface composite layers in the Al–6Mg alloy. X-ray diffraction and transmission electron microscopy data demonstrate that the 40–50 μm-thick layers formed by the UFM method contain uniformly distributed small (0.5–3 μm) or large (~15 μm) QCF particles with a volume fraction Vf of about 9% and 22%, respectively.
Compared to the annealed Al–6Mg alloy, a significant increase in wear resistance was observed only for the composite layer reinforced with small QCF particles. Large QCC particles, when destroyed during processing or wear tests, contribute to friction between the contacting bodies and reduce the wear resistance of the alloy. Microscopy (SEM and confocal) revealed changes in the wear mechanism: from micro-cutting/plowing in the QCC-reinforced layer to micro-cracks/destruction in the case of reinforcement with large QCC particles. To improve wear resistance, it is preferable to use small QCF particles both under quasi-static and dynamic conditions.
The hardness of the composite layers was measured using the Vickers microhardness method. The results showed that the hardness of the composite layers increased with an increase in the content of reinforcing particles and a decrease in their size. The wear resistance of the composite layers was assessed using sliding friction tests.
It has been established that the wear resistance of composite layers reinforced with quasicrystalline AlCuFe particles significantly exceeds the wear resistance of unreinforced Al–6Mg alloy. At the same time, the wear resistance depends on the size of the reinforcing particles, their distribution in the matrix and the hardness of the composite layer. The optimal combination of these factors ensures maximum wear resistance of the composite surface layer.
Author: BN Mordyuk, GI Prokopenko, Yu.V. Milman, MO Iefimov, KE Grinkevych, AV Sameljuk, IV Tkachenko
Institute: G. V. Kurdyumov Institute of Metal Physics, Academician Vernadsky Boulevard, 36, UA-03680 Kyiv, Ukraine, Frantsevich Institute for Problems of Materials Science, Krzhizhanovsky St., 3, UA-03142 Kyiv, Ukraine