Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9801433 | Science and Technology of Advanced Materials | 2005 | 10 Pages |
Abstract
Extruded Mg-6%Al-1%Zn (AZ61) alloy bar was subjected to 4-pass Equal Channel Angular Extrusion (ECAE) processing at 448-573 K. At the processing temperature of 448 K, extremely fine grains with the average grain size of 0.5 μm are formed as a result of dynamic recrystallization originated by fine Mg17Al12 (β) phase particles having 50-100 nm diameter dynamically-precipitated during ECAE processing. The sizes of both α matrix and β phase decrease with decreasing processing temperatures. In tensile test at room temperature under the strain rate of 1Ã10â3 s-1, tensile strength increases with decreasing ECAE processing temperatures due to fine grains, fine precipitates and residual strain hardening. Especially, highest strength of 351 MPa was achieved in the specimen ECAE-processed at 448 K. In addition to such high strength, elongation reaches 33% in that specimen. This specimen exhibits clear strain rate dependencies of both flow stress and elongation even at room temperature. As a result, higher elongation of 67% is obtained under low strain rate of 1Ã10â5 sâ1. In such specimen, non-basal slip and grain boundary sliding occur in addition to basal slip. Furthermore, there are grains with no dislocations, suggesting the occurrence of dynamic recovery. The contribution of all the deformation mechanisms would cause high ductility in fine-grained AZ61 alloy specimen with high strength.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Yu Yoshida, Keita Arai, Shota Itoh, Shigeharu Kamado, Yo Kojima,