Structure and properties of copper after large strain deformation

Kinga B. Rodak 1Rafal Molak 2Zbigniew Pakiela 2

1. Silesian University of Technology, Department of Materials Science, Krasińskiego 8, Katowice 40-019, Poland
2. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland

Abstract

Structure and properties of Cu in dependence on strain (from e~ 0,9 to e~ 15) during multi-axial compression processing at room temperature was investigated. The evolution of dislocation structure, misorientation distribution and crystallite size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The structure–flow stress relationship of multi-axial compression processing material at strains e~ 3,5 and e~ 5,5 is discussed. At strain e~ 3,5 the deformation microstructure indicated a mixture of elongated geometrically necessary boundaries (GNB) and  dislocation cell structures with dense dislocation tangles. Some regions revealed the wide bands which probably corresponded with the elongated initial grains, while other regions revealed fine dislocation bands (DBs). After e~ 5,5 the spacing of the DBs structure become smaller and microstructure has evolved into an approximately equiaxed subgrain structure, and the dislocation density of grain interiors seemed lower than those after e~ 3,5.  It is found that  processing does not produce any drastic changes in deformation structure and the microstructural refinement is slow. These results indicate that dynamic recovery and recrystallization play an important role during multi-axial compression process in this range of deformation. For this reason, a slight changes in the mechanical properties was observed. Due to small volume materials available for testing one way of measuring mechanical properties was using mini tensile test samples. In this work minisamples  with total length of 2,2mm were used. Digital Image Correlation method (DIC) was employed for the strain measurements in a uniaxial tensile test.

 

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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Kinga B. Rodak
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-06-18 12:34
Revised:   2009-07-29 10:11