Effect of Friction Stir Processing on the Kinetics of Superplastic Deformation in an Al-Mg-Zr Alloy


The effect of friction stir processing on the superplastic behavior of extruded Al-4Mg-1Zr was examined at 350 °C to 600 °C and at initial strain rates of 1×10−3 to 1 s−1. A combination of a fine grain size of 1.5 μm and high-angle grain boundaries in the friction stir-processed (FSP) alloy led to considerably enhanced superplastic ductility, much-reduced flow stress, and a shift to a higher optimum strain rate and lower optimum temperature. The as-extruded alloy exhibited the highest superplastic ductility of 1015 pct at 580 °C and an initial strain rate of 1×10−2s−1, whereas a maximum elongation of 1280 pct was obtained at 525 °C and an initial strain rate of 1×10−1s−1 for the FSP alloy. The FSP alloy exhibited enhanced superplastic deformation kinetics compared to that predicted by the constitutive relationship for superplasticity in fine-grained aluminum alloys. A possible origin for enhanced superplastic deformation kinetics in the FSP condition is proposed.


Materials Science and Engineering


National Science Foundation (U.S.)
United States. Office of Naval Research
University of Missouri Research Board

Keywords and Phrases

Extruded A1-4Mg-1Zr; Friction Stir Processing; Kinetics

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Document Type

Article - Journal

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© 2004 Springer Verlag, All rights reserved.

Publication Date

01 Jan 2004