Mechanism of Low-Temperature Superplastic Deformation in Aluminum Alloys Containing a Dispersion of Nanoscale Al3(Sc,Zr) Particles
The ultrafine grained (UFG) structure with an average size of ∼0.8 μm was produced in an Al-Li-Mg-Sc alloy by equal-channel angular extrusion (ECAE) at 325oC with a total strain of ~16. Superplastic behavior was examined in the temperature range 150-250oC at strain rates ranging from 10-5 to 10-2 s-1. A maximum elongation-to-failure of 440% was recorded at 175oC (~0.5 Tm, where Tm is the melting point) and a strain rate of 2.8×10-5 s-1 with the corresponded strain rate sensitivity coefficient of 0.32. Mechanisms of low-temperature superplasticity (LTSP) and high-strain-rate superplasticity (HTSP) are essentially the same. The difference between superplastic behaviors at low and high temperatures is attributed to applied stress.
Eiichi Sato, Goroh Itoh, Yoshimasa Takayama, Koichi Kitazono, Koji Morita, Takaomi Itoi and Junya Kobayashi
R. Kaibyshev "Mechanism of Low-Temperature Superplastic Deformation in Aluminum Alloys Containing a Dispersion of Nanoscale Al3(Sc,Zr) Particles", Materials Science Forum, Vols. 838-839, pp. 150-156, 2016