Title: Development of nanostructure in AZ31 magnesium alloy during accumulative roll bonding process

Authors: A. Sadeghi, A. Akbarzadeh

Addresses: Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11155-9466, Tehran, Iran. ' Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11155-9466, Tehran, Iran

Abstract: Accumulative roll bonding (ARB) is one of the effective severe plastic deformation methods for developing very fine grained nanostructures. In the present work, grain refinement and microstructural changes of magnesium AZ31 alloy during ARB process was investigated. Sheet specimens up to 256 cold welded layers (eight ARB cycles) were prepared. Evolution of the microstructure was observed using optical microscopy. It is shown that various mechanisms such as rotational recrystallisation (RRX) and twinning are involved in grain refinement at different passes. Increasing the number of ARB cycles leads to an ultra fine grain (UFG) microstructure (almost 500 nm) surrounded by nanoscale grain zones (almost 120 nm). The microstructural evolution is explained by grain refinement along the deformation bands by means of geometrical recrystallisation, RRX and progressive lattice rotation.

Keywords: nanostructures; ultra fine grain; UFG; microstructure; accumulative roll bonding; ARB; severe plastic deformation; SPD; magnesium alloys; nanotechnology.

DOI: 10.1504/IJNM.2010.033864

International Journal of Nanomanufacturing, 2010 Vol.5 No.3/4, pp.225 - 231

Available online: 02 Jul 2010 *

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