Plastic deformation behavior of Mg97Zn1Y2 extruded alloys
(1. Division of Materials and Manufacturing Science, Graduate School of Engineering,
Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871, Japan;
2. Department of Materials Science, Kumamoto University,
2-39-1, Kurokami, Kumamoto 860-8555, Japan;
3. National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan)
Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871, Japan;
2. Department of Materials Science, Kumamoto University,
2-39-1, Kurokami, Kumamoto 860-8555, Japan;
3. National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047, Japan)
Abstract: The mechanical properties of the Mg97Zn1Y2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%−25%, were examined by compression tests and cyclic tension−compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 (molar fraction, %), which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.
Key words: plastic deformation; yield stress; LPSO-phase; dislocation; twinning