https://material.karlov.mff.cuni.cz/people/janecek/studenti/FyzMetNano/Estrin_AM61_2013_782.pdf

Extreme grain refinement by severe plastic deformation: A wealth of challenging science

Grain refinement is known to lead to improvements in strength and wear resistance. Inherent processing involved in grain refinement alter both the bulk and the surface of a material, leading to changes in grain boundary density, orientation, and residual stress. Ultimately, these surface changes can have an impact on electrochemical behavior and, consequently, corrosion susceptibility as evidenced by the large number of studies on the effect of grain size on corrosion, which span a range of materials and test environments. However, there has been limited work on developing a fundamental understanding of how grain refinement and more generally how grain size affects the corrosion resistance of an alloy. Existing literature is often contradictory, even within the same alloy class, and a coherent understanding of how grain size influences corrosion response is largely lacking. A survey of previous work related to the relationship between grain size and corrosion resistance for a number of light meta...

Effect of Grain Size on Corrosion: A Review

Forming alloys with impurity elements is a routine method for modifying the properties of metals. An alternative approach involves the incorporation of interfaces into the crystalline lattice to enhance the metal's properties without changing its chemical composition. The introduction of high-density interfaces in nanostructured materials results in greatly improved strength and hardness; however, interfaces at the nanoscale show low stability. In this Review, I discuss recent developments in the stabilization of nanostructured metals by modifying the architectures of their interfaces. The amount, structure and distribution of several types of interfaces, such as high- and low-angle grain boundaries and twin boundaries, are discussed. I survey several examples of materials with nanotwinned and nanolaminated structures, as well as with gradient nanostructures, describing the techniques used to produce such samples and tracing their exceptional performances back to the nanoscale architectures of their interfaces. The incorporation of structural defects, in particular of interfaces, into crystalline lattices results in enhanced material properties. In this Review, different types of boundaries and interfaces are discussed, including high- and low-angle grain boundaries, twin boundaries, nanotwinned and nanolaminated structures, and gradient nanostructures.

Stabilizing nanostructures in metals using grain and twin boundary architectures

Atomistic modeling of interfaces and their impact on microstructure and properties

Texture evolution in equal-channel angular extrusion

Microstructure and texture evolution of pure copper (99.95%) after equal-channel angular pressing (ECAP) with route Bc up to 12 passes and subsequent heat treatment were investigated. After deformation the samples were annealed at different temperatures. The deformed and annealed states were characterized by X-ray pole figures, electron back scatter diffraction (EBSD), TEM and microhardness tests. It was shown that the observed texture and microstructure changes during subsequent annealing have to be associated with discontinuous recrystallization. The study revealed a very low thermal stability of this ECAP processed pure copper. The observed decrease of the apparent activation energy for recrystallization is most likely due to improved nucleation conditions of ECAP deformed material.

Thermal stability of ECAP processed pure copper

Annealing behaviour of cold rolled aluminum alloy in a high magnetic field

Magnetically enhanced recrystallization in an aluminum alloy

Copperisoneofthemostimportantmaterialsusedforelectricalconnectorswithahighthermalandelectricialconductivity,andthereisanongoing demand to improve its mechanical properties without sacriﬁcing other beneﬁcial properties. A possible approach to achieving this aimis to use the method of severe plastic deformation to obtain an ultraﬁne grained microstructure. Signiﬁcant grain reﬁnement obtained by equalchannelangularpressing(ECAP)leadstoanimprovementofmechanical,microstructuralandphysicalproperties.Thispapergivesanoverviewof a range of the properties that can be achieved by ECAP processing of pure copper including microstructural features, thermal stability,thermal conductivity and corrosion resistance. [doi:10.2320/matertrans.ME200717](Received July 10, 2007; Accepted August 10, 2007; Published September 28, 2007)Keywords: copper, severe plastic deformation, equal channel angualar pressing, mechanical properties, thermal stability, thermalconductivity, corrosion behaviour

A Portrait of Copper Processed by Equal Channel Angular Pressing

A laser powered heating stage designed for application in high vacuum environment of a scanning electron microscope (SEM) is presented. It was developed to observe and characterize microstructural changes in crystalline materials at elevated temperatures up to 1000°C. The approach utilizes the power output of a commercial infrared diode laser in order to heat up specimens without interference with the electronic system of the SEM. The heating stage can be used in combination with any standard characterization technique applicable for SEMs—electron backscatter diffraction, orientation contrast imaging, x-ray energy dispersive spectrometry, etc. The results of test measurements are presented.

Xenia Molodova

Papers

Thermal stability of ECAP processed pure copper

Annealing behaviour of cold rolled aluminum alloy in a high magnetic field

Magnetically enhanced recrystallization in an aluminum alloy

A Portrait of Copper Processed by Equal Channel Angular Pressing

Laser powered heating stage in a scanning electron microscope for microstructural investigations at elevated temperatures.