Výzkum poruch krystalické mřížky v kovových povlacích připravených studeným naprašováním

Chmúrny, Daniel

Thermal stability of copper and nickel samples prepared by gas dynamic cold spraying and high pressure torsion were studied by means of positron lifetime spectroscopy and Vickers hardness test. These groups of the same materials prepared by fundamentally different methods were then compared in terms of Vickers hardness, mean positron life- time, separate positron lifetime components examination, volume of clusters of vacancies and their concentration, dislocation densities. This comparison revealed differences in thermal stability, inner defect behavior and homogeneity between the samples prepared by cold spraying and those by high pressure torsion. However, both methods manifested qualitative similarities as well. The spectra of the cold sprayed materials were calculated via simple positron trapping model while for calculations regarding those prepared by high pressure torsion the diffusion trapping model was needed due to strongly inhomoge- neous spatial distribution of defects. Annealing leads to a recrystallized state independent on the history of the concrete specimen. 1

guest :: login Digital Repository
		Search		Submit		Help		About