長周期相を有するMg-Cu-Y合金の組織と機械的特性

抄録

Microstructure and mechanical properties of the Mg-Cu-Y alloy were investigated. Volume fraction of a long period ordered (LPO) phase was increased with the increasing of Cu and Y contents in the Mg_<100-x-y>Cu_xY_y (x=1〜3, y=2〜6 at. %) alloys. Yield strength of Mg-Cu-Y alloy tends to increase with the increasing volume fraction of the LPO phase, while elongation decreases. The Mg_<91>Cu_3Y_6 cast alloy indicated yield strength of 242MPa, and high yield strength above 200 MPa was maintained at 523K. The Mg_<91>Cu_3Y_6 cast alloy exhibited high strength over a wide temperature range compared with commercial Mg alloys (AZ91D or WE54-T6). The Mg_<91>Cu_3Y_6 annealed sheet exhibited yield strength and an elongation of 412MPa and 6%, respectively, at room temperature, and 254MPa and 24%, respectively at 523K. Specific strength of the Mg_<91>Cu_3Y_6 annealed sheet was 198kN・m/kg which is higher than that of commercial Mg alloy (AZ31) or super extra duralumin (A7075-T6).