Microscopic and X-Ray Analysis of the Surface Changes in Aluminum Alloys during Friction

Abstract

The effect of the introduction of additives of low-melting alloying elements in antifriction aluminum alloys on a change in the surface after tribological tests is estimated. Compositions are described and sample preparation is performed. For the study, a combination of electron microscopy methods (with elemental analysis) and probe microscopy (with the modes of spreading current and thermal-conductivity analysis) are used. It is shown that after heat treatment, the phase components acquire a globular shape in both alloys. Grain deformation, soft phase release to the surface, and mass transfer take place during the friction process. The hard phase components of the shoe material act as an abrasive, while mass transfer forms a film of secondary structures of variable thickness on the roller (under certain conditions, the film becomes thicker, which can lead to scuffing). The analysis of sections allows the presence of a near-surface layer (50–100 µm thick) with a modified structure to be established. The SPM method is used to establish that the thermal conductivity map at the micro level correlates with the electrical conductivity map. X-ray structural analysis of the surfaces carried out before and after tribological tests showed that the lattice spacing decreased, lattice deformation increased, and texture appeared.