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Combination of ECAP and Hydrostatic Extrusion for ultra-fine grain (UFG) microstructure generation in 99.98% nickel. |
| Mariusz Kulczyk 2,3, Waclaw Pachla 3, Anna Swiderska - Sroda 3, Nikolay Krasilnikov 1,4, Agnieszka Mazur 3, Witold Łojkowski 3, Krzysztof J. Kurzydlowski 2 |
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1. Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, K.Marks St.12, Ufa 450000, Russian Federation |
| Abstract |
Ultra-fine grained materials attract considerable attention, due to their high strength. They are usually obtained by severe plastic deformation processes. Extensive research is done to produce bulk nanostructured metals. The most effective method from the point of grain refinement is high pressure torsion, however it involves very small material volume. The goal of the present work is to demonstrate, that bulk, ultra-fine grained microstructure can be obtained in high purity nickel by combination of ECAP and hydrostatic extrusion (HE) processes. Deformation has involved eight times ECAP followed by eight times HE to 3mm wire with total true strain of ~12.5. The resulting microstructure is characterized by light and TEM microscopy and mechanical properties. Addition of HE to ECAP-ed sample has led to significant grain size refinement, from 330nm to 160nm, and to apparent increase in the microstructure homogeneity. Microstructure transformation has led to appropriate improvement in strength properties, increase of yield stress by 78% in comparison to pure ECAP. Combination of ECAP and HE has enabled to achieve much better properties than application of each individual one and show to be promising in manufacturing of bulk UFG nickel. |