Abstract
A very fine-grained Al-1.5wt.%Mg alloy stabilised by small amounts of Sc and Zr was prepared using ECAP. The values of ductility and strain rate sensitivity parameter m corresponding to superplastic behaviour were found in tensile tests at temperatures above 573 K. The optimum superplastic behaviour was observed at strain rates of the order of 10^-2.s^-1. The surface examination of slightly strained samples by atom force microscopy revealed that grain boundary sliding did not occur at all interfaces. The diversity of misorientation angles is probably responsible for this effect.

Key words
Al-Mg-Sc-Zr alloy, ECAP, submicrocrystalline microstructure, uperplasticity, grain boundary sliding

Full text (998 KB)