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Fracture toughness in direct extruded Mg–Al–Zn alloys

Published online by Cambridge University Press:  31 January 2011

Hidetoshi Somekawa*
Affiliation:
Structural Metals Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
Han S. Kim
Affiliation:
Structural Metals Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
Alok Singh
Affiliation:
Structural Metals Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
Toshiji Mukai
Affiliation:
Structural Metals Center, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan
*
a)Address all correspondence to this author. e-mail: SOMEKAWA.Hidetoshi@nims.go.jp
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Abstract

Fracture toughness and its deformed structures were investigated on a Mg–3Al–1Zn (AZ31) alloy processed by direct extrusion. The average grain sizes of the alloy after extrusion at temperatures of 473 and 573 K were 4.0 and 14.5 μm, respectively (i.e., fine-grained and coarse-grained alloys). The plane-strain fracture toughness, KIC, as determined by stretched zone analysis in fine-grained and coarse-grained alloys was estimated to be 24.9 and 22.7 MPam1/2, respectively. Microstructural observations of the fine-grained alloy after fracture toughness testing showed that non-basal slip and grain-boundary sliding was activated even at room temperature. In addition, the {10-12} deformation twins were observed despite the fine-grained structures. However, the fraction of deformation twins was reduced with grain refinement, which related to the enhancement of fracture toughness with grain refinement.

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Articles
Copyright
Copyright © Materials Research Society 2007

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References

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