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Developing SPD Methods Processing Bulk Nanostructured Materials with Enhanced Properties
Valiev, R . Z . 대한금속재료학회(대한금속학회) 2001 METALS AND MATERIALS International Vol.7 No.5
Severe plastic deformation (SPD), i.e. intense plastic straining under high pressure, is an innovative technique for processing ultrafine-grained nanostructured metals and alloys. SPD fabricated nanostructures can lead to novel properties, which, however, depend strongly on the processing parameters. This paper focuses on examples of attaining enhanced mechanical properties in several metals and alloys, subjected to severe plastic deformation. In addition, the relationships among the processing conditions, microstructures and properties of the materials produced by SPD are considered.
Photoluminescence and Magneto-optical Properties of Zn1−xMnxO
율다세프,강태원,Vasiliy O. Pelenovich,Uygun V. Valiev 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3
Zn1−xMnxO thin films on quartz substrates with a low concentration of Mn (1%) were prepared by using ultrasonic spray pyrolysis. Photoluminescence, optical absorption, and magnetic circular dichroism (MCD) measurements were conducted in order to study the optical and the magnetic properties of Zn0.99Mn0.01O. The free exciton lines are dominant in the spectra of these samples, which indicates a high crystal quality for the films. Magneto-optical measurements show a significant MCD at the band edge of Zn0.99Mn0.01O at room temperature.
Textures in Nanostructured Metals Processed by Severe Plastic Deformation
Alexandrov, Igor V.,Dubravina, Anna A.,Kilmametov, Ascar R.,Kazykhanov, Vil U.,Valiev, Ruslan Z. 대한금속재료학회 2003 METALS AND MATERIALS International Vol.9 No.2
This work demonstrates and analyzes the experimental results of the crystallographic texture formation processes in pure metals with a different type of crystal lattice, which were subjected to severe plastic deformation (SPD) applying various techniques such as high pressure torsion (HPT) and equal-channel angular pressing (ECAP).
Effect of surface etching on the tensile behavior of coarse- and ultrafine-grained pure titanium
Baek, Seung Mi,Polyakov, Alexander V.,Moon, Ji Hyun,Semenova, Irina P.,Valiev, Ruslan Z.,Kim, Hyoung Seop Elsevier Sequoia 2017 Materials science & engineering Structural materia Vol.707 No.-
<P><B>Abstract</B></P> <P>For metallic biomaterials, surface treatment is essential for improving osseointegration. Acid etching is the basic method used for removing undesirable contaminants and increasing surface roughness. Although the obvious effect of the etching process is a change in surface characteristics, interestingly, surface etching can also affect the tensile properties of the material. In this paper, the influence of etching on the tensile behavior of pure titanium was investigated. The surface morphology and tensile properties of coarse- and ultrafine-grained pure titanium specimens were examined after hydrofluoric acid etching, in terms of the etching time. The ultrafine-grained titanium was prepared using conform equal-channel angular pressing to enhance the mechanical properties of the pure titanium. Micro-scale pores were observed, and tensile strength was decreased in the 1min etched coarse-grained titanium. The 20min etched coarse-grained specimen and the ultrafine-grained specimen with relatively homogeneous pore structure maintained or slightly increased their tensile strengths. These results provide a new foundation for the production of reliable metallic biomaterials.</P>
Kim, J.G.,Enikeev, N.A.,Abramova, M.M.,Park, B.H.,Valiev, R.Z.,Kim, H.S. Elsevier 2017 Materials science & engineering. properties, micro Vol.682 No.-
<P><B>Abstract</B></P> <P>The initial grain size of TWIP steel can affect the deformation mechanism during the HPT processes and the mechanical properties of severely deformed TWIP steels, contrary to the common belief that responses to the severe plastic deformation of metallic materials are not affected by initial grain size.</P>
Microstructure, Texture and Mechanical Properties of Titanium Grade 2 Processed by ECAP (Route C)
M. Wroński,K. Wierzbanowski,D. Wojtas,E. Szyfner,R. Z. Valiev,J. Kawałko,K. Berent,K. Sztwiertnia 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.4
In the present work the properties of titanium grade 2 after ECAP processing with original route and regimes (route C, channelangle = 120°, deformation temperature 300 °C, number of passes up to 8) were examined. Texture development andmicrostructure parameters after ECAP processing and after recrystallization were determined using electron back scatterdiff raction and analysed. A signifi cant increase of the mechanical strength accompanied by some increase of ductility wasobserved in the deformed samples. The kernel average misorientation and average grain orientation spread were stronglyincreased after deformation, which confi rms the material refi nement and fragmentation. The proportion of low angle boundariesincreased after four ECAP passes, but after four consecutive passes high angle grain boundaries became predominant. Nodeformation twins were observed after four and eight ECAP passes. The material recrystallized after deformation retaineda fi ne grain microstructure. The textures of deformed and recrystallized samples were determined. It was found that textureafter 8 passes is more homogeneous that that after 4 passes, which partly explains higher ductility of this fi rst sample.