2004 Volume 90 Issue 1 Pages 21-26
Thin Mg-Al alloy, AZ91D sheets annealed around the temperature between 0% and 100% recrystallization have been prepared and tensed at high temperatures and with several strain-rates. Both the total elongation and strain-rate sensitivity m have been obtained and discussed.
The values of total elongation have exceeded over 110% at all testing temperatures and with all strain-rates except high strain-rate at testing temperature of 573K, and the maximum total elongation of 270% has been obtained. The m values have indicated 0.5 in range of 1.0×10-4s1 to 2.5×10-4s-1 and maintained about 0.3 up to the neighborhood of 1.0 × 10-2s-1.
The activation energy required for superplastic deformation has been calculated to be about 70 kJ·mol-1, which is almost same of the activation energy for self-diffusional grain boundary coefficient in Mg. Therefore, the superplastic deformation of AZ91D annealed around the temperature between 0% and 100% recrystallization has been accommodated by grain boundary diffusion.
