Nanocrystalline materials manufactured by torsion under pressure of 2 GPa

Jan Kusnierz ,  Jan M. Dutkiewicz ,  Mariusz Kurowski 

Polish Academy of Sciences, Institute of Metallurgy and Materials Sciences (IMIM PAN), Reymonta 25, Kraków 30-059, Poland

Abstract

Improved mechanical properties of bulk materials with ultra-fine grained (UFG) structure (nanostructure) are mostly reported, which are manifested by greater strength, hardness and ductility in comparison with conventional coarse-grained materials; also the high-speed superplasticity flow is reported. In metal alloys with UFG structure manufactured by severe plastic deformation (SPD) the formation of metastable states or solid solutions in immiscible systems is observed.

SPD is commonly proposed as a method to obtain UFG microstructure. Such methods of processing by means of SPD like Equal-Channel Angular Pressing (ECAP), Accumulative Roll-Bonding (ARB), High Pressure Torsion (HPT) and Mechanical Alloying (MA) are commonly used recently. ECAP type of processing for example enables obtaining of bulk samples of relatively great dimensions and free from porosity in opposition to the methods based on powder metallurgy, rapid cooling or crystallization from gaseous phases. The ARB method in turns, can supply semi-final products in the form of sheets, which can be directly used for further work forming operation. High pressure torsion, although can't supply big dimension samples, it leads generally to highest degree of grain refinement. Mechanical Alloying (MA) by ball milling and successive compacting offers the method to extend the solubility limit.

The main objective of the paper is to present the influence of the phenomenon of intensive shear deformation during High Pressure Torsion (HPT) processing on the changes of structure, grain size, mechanical properties and solid solubility. Study is performed with metals and mostly metal alloys like Ti, Al and Cu alloys, severely deformed up to high deformation degree.

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium I, by Jan Kusnierz
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-16 08:34
Revised:   2009-06-07 00:44
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