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Excellent mechanical properties of UFG metals and alloys, subjected to combination of severe plastic deformation methods.

Nikolay Krasilnikov 1,3Witold Łojkowski 2Ruslan Z. Valiev 1

1. Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, K.Marks St.12, Ufa 450000, Russian Federation
2. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland
3. Ulyanovsk State University (UlGU), L.Tolstoy, 42, Ulyanovsk 432700, Russian Federation

Abstract

The Ni and Al-based alloy 2024 after different methods of severe plastic deformation (SPD) are investigated. The equal channel angular pressing (ECAP) and cold rolling nickel, subjected also to high-pressure torsion (HPT), is characterized of large strain degree, homogeneous structure with grain size 120 nm and shows at room temperature the record strength with ultimate tensile stress (UTS) (1270 MPa), but limited plasticity (6%). The combination of high strength and plasticity managed to be obtained using the annealing at 200C of Ni after ECAP and rolling. This treatment of Ni leads to UTS about 900 MPa and ductility 12%.
Using HPT under pressure 6 GPa has allowed to obtain nanostructured samples of Al-based alloy 2024 with grain size 70 nm and high-angle grain boundaries in result of torsion (5 turns) at room temperature. The nanostructured alloy at room temperature demonstrated record UTS above 1100 MPa, and superplastic behavior at temperature higher then 300С. The microhardness of nanostructured alloy after superplastic deformation was 1.5 GPa and was more than after standard treatment of coarse-grained state of alloy (1.2 GPa).
Opportunity of achievement in metals and alloys of combination high strength and good ductility opens perspectives of its application in industry, particularly, for mirco-systems and for details with complex geometry, obtained due to superplastic forming.

 

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Related papers

Presentation: oral at E-MRS Fall Meeting 2004, Symposium I, by Nikolay A. Krasilnikov
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-06-17 11:49
Revised:   2009-06-08 12:55