3725451505

Abstract

There are presented the results of the studies of the subsurface zonę created in aluminium and its alloys during sliding or other surface modification treatments. The application of the positron annihilation techniques due to their high sensitivity to crystal lattice defects enabled to determine defects profiles in the subsurface zonę. The positron annihilation studies were correlated with other conventional measurements applied in tribology, i.e. microhardness measurements, scanning electron microscopy, X-ray diffraction and in a special case stress distribution calculated theoretically.

It was shown that the positron annihilation spectroscopy is a useful tool for profiling of the subsurface zonę created during sliding even for light metals their alloys and composites. The total rangę of the subsurface zonę detected by the positron annihilation extends from 50 pm to 450 pm depending on the materiał studied and surface modification treatment. Additionally, the type of the main defects can be determined. The studies of the pure aluminium samples after dry sliding enabled to fmd the defect concentration of vacancy type in the depth less then 1 pm and to correlate its value with the size of crystallites. It supports the conclusion on recovery processes taking place in this layer. There was madę the attempt to apply the Doppler broadening coincidence spectroscopy to the studies of aluminium alloy and composite.

In view of the interdisciplinary character the present thesis enclose also the review of the basie issues of tribology, measurement methods applied to the subsurface zonę studies and positron annihilation experimental techniąues.