Author: Владимир
Last saved by: Warrior

Specialization: 010700/03 Physics of Condensed Matter
Curriculum: 24 Nanoelectronics
Program manager :prof. А.S. Shulakov
Department of solid state electronics
Scientific advisor: prof. V.K. Adamchuk 
Reviewer: prof. O.F. Vyvenko

Studies of Nanostructured Al-based systems by scanning probe microscopy
E.P.Luzina

At the beginning of last century, it was shown that the microstructure of the material effect on its macroscopic properties (strength, elasticity, fragility, etc.). In recent decades, there were possibilities for investigating structures with submicron grain size (AFM, SEM), and tests on the mechanical properties showed that these alloys have good prospects of application in industry due to their high strength and ductility. Mechanisms of hardening alloys subjected to severe plastic deformation (SPD) may be different, such as the allocation point of crystals of compounds from the solid solution, the formation of coherent matrix of another compound in the metal, increasing the share of grain boundary phase, which prevents the spread of vacancies and dislocations. 
The aim of this work was to study the structural changes of aluminum alloys after severe plastic deformation and to define the basic type of hardening mechanism, whose contribution has resulted such improvement of the mechanical properties. 	
In the present work the structure of aluminum subjected to SPD was studed and it was compared with the original aluminium structure. The developed complex of preparation allows to achieve a flat surface with the mean square roughness of 8 nm, that allows us to study it by optical methods, AFM, SEM, and also to observe and analyze diffraction  at the different points. As a result of the following conclusions can be:
1.	The samples are Al alloy with Fe particles, with an average size of 1-2 microns,  no changes in chemical composition or new phases after SPD were found (according to X-ray analysis).
2.	Samples of original and nanostructured Al are grain structure with average size of a monocrystal grain about 500 microns and 220 nm, respectively (according to optical microscopy, AFM, SEM and electron diffraction)
3.	SPD has led to a refinement of the structure of the sample to 3 orders of magnitude.
4.	It is expected increase in yield strength of nanostructured aluminum retaining the Hall-Petch dependence, but with the exponent for d different from the classical -0.5
5.	The main mechanism that leads to an increase in yield strength of nanostructured aluminum connected with an increasing of the number of defects (border), leading to a significant reduction of dislocation mobility. 

The list of the publications

«AFM investigations of the constructive materials under extreme temperature and mechanical influence», Ulyanov P.G., Usachev D.U., Mikhaylova(Luzina) E.P., Luzin D.V. Thesis of the second Nanotechnology interenational forum, Rosnano, 2009.