Dislocation structure of nickel after cavitation erosion in chemically active and surface-active media

Abstract

Microhardness measurements and x-ray diffraction analysis are used to study changes in these properties during such erosion. However, the use of the latter in this case is complicated first by the fact that the x rays penetrate fairly deeply into the material, and structural changes in the thin surface layer are hard to distinguish on the background observed for thedeeper layers; second, the short length of the x rays and their scattering by the rough surface created during testing make it impossible to study specimens during long periods of cavitation erosion. As was shown in [I], one very promising method in his regard is that of ferromagnetic resonance (FR), in which the wavelengths are much longer. By virtue of the skin effect, an shf electromagnetic field penetrates about i ~m into the metal, and broadening of the FR lines in this case reflects structural changes in the surface layer only. Since the width of the FR lines (AH) in the deformed ferromagnetic material is linearly dependent on dislocation density [2] and is nearly independent of the number of point defects [3], then the function AH = f(T) will reflect the change in the dislocation structure of the surface layer of specimens in cavitation erosion tests.