Microstructure and Mechanical Behavior of Friction Stir Processed Ultrafine Grained Al-Mg-Sc Alloy


Twin-roll cast (TRC) Al-Mg-Sc alloy was frictionstir processed (FSP) to obtain ultrafine grained (UFG) microstructure. Average grain size of TRC alloy in as-received (AR) condition was 19.0 ± 27.2 μm. The grain size reduced to 0.73 ± 0.44 μm after FSP. About 80% of the grains were smaller than 1 μm in FSP condition. FSP resulted into 80% of the grain boundaries to have high angle grain boundary (HAGBs) character. Uniaxial tensile testing of UFG alloy showed an increase in yield strength (YS) and ultimate tensile strength (UTS) (by ∼100 MPa each) of the alloy with a very marginal decrease in total and uniform elongation (total - 27% in AR and 24% in UFG and uniform - 19% in AR and 14% in UFG). A theoretical model predicted that the grain refinement cannot take place via discontinuous dynamic recrystallization. Zener pinning model correctly predicted the grain size distribution for UFG alloy. From work hardening behaviors in both the conditions, it was concluded that grain boundary spacing is more important than the character of grain boundaries for influencing extent of uniform deformation of an alloy


Mechanical and Aerospace Engineering

Second Department

Materials Science and Engineering

Keywords and Phrases

EBSD; Friction Stir Processing; Grain Growth; Grain Refinement; Mechanical Characterization

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2011 Elsevier, All rights reserved.

Publication Date

01 Jul 2011