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Development of microstructure and mechanical properties in nickel deformed by hydrostatic extrusion

Mariusz Kulczyk 1Andrzej Mazur 1Witold Łojkowski 1Ryszard Diduszko 3Halina Garbacz 2Malgorzata Lewandowska 2Waclaw Pachla 1

1. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
2. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland
3. Institute of Electronic Materials Technology (ITME), Wólczyńska 133, Warszawa 01-919, Poland

Abstract

Bulk, ultra-fine grained metals can be produced by severe plastic deformation (SPD) techniques, as equal channel angular pressing (ECAP), high pressure torsion (HPT) cumulative rolling (CR) or multiple forging (MF). SPD technique combines intense plastic straining under high imposed pressure.
Recently, the hydrostatic extrusion (HE) gains more attention as the SPD process [1]. The goal of present work is to demonstrate that by HE the formation of bulk, ultra-fine grained microstructure can be obtained in commercial purity nickel. Deformation is performed at room temperature to wire of diameter 3mm with the total true strain ~3.8. The structure is characterized by light microscopy, TEM and XRD methods and the mechanical properties by tensile tests and microhardness measurements.
It was found that the HE leads to significant refinement of the material microstructure. The remarkable microstructure refinement by three orders of magnitude (initial 200 micrometer grains --> final 200 nm subgrains) was observed). Transformation in microstructure is accompanied by an improvement of the mechanical properties. Results obtained are discussed in terms of microstructure development during the consecutive HE steps.

[1] see contributions to present conference

 

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Related papers

Presentation: poster at E-MRS Fall Meeting 2004, Symposium I, by Mariusz Kulczyk
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-06-07 10:10
Revised:   2009-06-08 12:55