Composite Microhardness of Quartz — Al Structures

Phys. Status Solidi (c)

Stolyarova

2007

Al based nanocomposite coatings on Cu and glass substrates were obtained in the conditions of severe shear stresses by deformation scheme similar to that of friction. Structure, composition and micromechanical properties were investigated using AFM, XRD, SIMS, electron, optical microscopy and precision microindentation techniques. Coatings are characterized by the high microhardness and good adhesion to the substrates. This is determined by the formation of nanostructured Al-oxide composite stabilized by the presence of oxidized interlayers, which are barriers for the grain growth and intermetallic phase formation. The annealing in vacuum leads to the development of oxygen redistribution processes on interphase boundaries in coatings according to the metal-oxygen interaction thermodynamics. (Al, In, Mg). On the other hand, it is known, that severe plastic deformation is one of the method for obtaining nanostructured metals with good complex of mechanical properties due to the formation of dislocationdisclination substructure with the grain size of 10-100 nm. According to the empirical Hall-Petch equation, the dispersion of crystalline structure at T≤0.5·T m promotes essential strengthening of the material:

Section: Resultssupporting

confidence: 91%

Nanostructured metal/oxide coatings

Muktepavela

Phys. Status Solidi (c)

Stolyarova

2007

“…where t is contact time in solid state joint (t ≈ 60 s), D is equal to about 3·10 -10 cm 2 /s. This result seems reasonable and is in good agreement with the known diffusion coefficients for Al/quartz systems in wetting experiments at high temperatures (700-800˚C) [20]. Such agreement can be explained by the high density of point defects in the surface layers of oxide and formation of nanostructure in metal during plastic flow.…”

Section: Resultssupporting

confidence: 88%

Effect of Mechanoactivation on Interfacial Interaction in Metal/Oxide Systems

Muktepavela

Stolyarova

2006

DDF

Properties of interfaces in solid state metal/oxide joints (Al/SiO2, Al/MgO, Al/glass, Mg/MgO, Mg/SiO2, In/glass etc.) are reported. The interfaces were formed by plastic deformation of metal on the oxide surface at room temperature. Their structure, chemical composition, and micromechanical properties were studied by the AFM, XRD, SIMS, optical microscopy, and precision microindentation techniques. A noticeable adhesion was observed for metals with high affinity for oxygen and only in the regions of the maximum shear stress. Formation of an interfacial reaction zone with an oxygen concentration gradient is detected. In this zone metals are nanostructured and noticeably hardened. The effect of mechanoactivation is considered as a result of physical and chemical interaction and formation of nanostructures in deformed metal/oxide systems.

Adhesion and interfacial reactions on metal/oxide interface during plastic deformation at room temperature

Muktepavela¹,

Mat.-wiss. u. Werkstofftech.

Skvortsova

et al. 2005

Properties of interfaces in solid state metal/oxide joints (Al/SiO 2 , Al/MgO, Al/glass, Mg/MgO, Mg/SiO 2 , In/glass etc.) are reported. The interfaces were formed at plastic deformation of metal on the oxide surface at room temperature. Their structure, chemical composition, and micromechanical properties were studied by the AFM, XRD, SIMS, optical microscopy, and precision microindentation techniques. A noticeable adhesion was observed for metals with high affinity for oxygen and only in the regions of the maximum shear stress. Formation of an interfacial reaction zone with an oxygen concentration gradient is detected. In this zone metals are nanostructured and noticeably hardened. The effect of mechanoactivation is considered as a result of physical and chemical interaction and formation of nanostructures in deformed metal/oxide systems.Key words: metal/oxide interfaces, adhesion, interfacial reaction, mechanoactivation, nanostructure.