Superplastic Deformation Behavior in Mg-Al Alloy, AZ91, Grain Refined by Isothermal-rolling
The isothermal rolling mill, which allows a large preform for materials having poor workability, has been developed. AZ91 alloy sheets made from Mg–9Al–1Zn tempered to a fine grain size by recrystallization have been prepared and tensioned at elevated temperatures. The maximum total elongation reached 170% and the <i>m</i>-value was found to be 0.5 in range of 1.0×10<sup>−4</sup> s<sup>−1</sup> to 2.5×10<sup>−4</sup> s<sup>−1</sup> except at the testing temperature of 573 K.<br>The activation energy required for high temperature deformation has been calculated to be about 124 kJ·mol<sup>−1</sup>, which is almost equal to the self-diffusion energy of Mg for volume diffusion. Therefore, the superplastic deformation of the recrystallized AZ91 has been accompanied by a volume diffusion.
- ISIJ international
ISIJ international 46(5), 694-697, 2006-05-15
The Iron and Steel Institute of Japan