OS0305 長周期積層構造型Mg-Zn-Y合金押出材の熱的安定性と機械的特性(先端材料システムの力学とメゾスケールモデリング,オーガナイズドセッション)

概要

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Mg-Zn-Y alloy with a long period stacking ordered (LPSO) structure was produced by extrusion, and the effects of annealing on its microstructure and mechanical properties were investigated. Heat treatment at temperatures up to 623 K improved the elongation of the alloy from 5.4 % to 9.6 % but caused no changes in either yield stress or tensile strength, which remained at 391 MPa and 432 MPa, respectively, because the LPSO phase prevented grain growth, and the α-Mg phase kept the fine grain sizes and kink deformation remain in the LPSO phase and the Mg_3Zn_3Y_2 phases finely dispersed. When the alloy was heat treated at 773 K, the α-Mg and Mg_3Zn_3Y_2 phases became coarse, which reduced the yield stress and tensile strength to 210 MPa and 320 MPa, respectively, while the elongation improved to 23 %. The study showed that the ductility of the alloy could be improved while keeping the strength high by heat treatment.
2009-07-24