超軽量Mg-Li-Al合金の熱処理特性および機械的性質に及ぼす添加元素の影響 Effect of additional elements on heat treatment characteristics and mechanical properties of superlight Mg-Li-Al alloys
In this study, 0.5 mass%Ca, Si, Zr or 1 mass%Y as a fourth alloying element was added to Mg–20 mass%Li–10 mass%Al alloy in order to restrict recrystallization and growth of recrystallized grains. Effects of the alloying elements on heat treatment characteristics and tensile properties of the warm-rolled specimens were investigated. Quenching of the specimens after isothermal holding at the temperature more than 200°C for 1 h results in increasing hardness and strength and in decreasing elongation, because aluminum is resolved into the β phase. Recrystallized grains of the quaternary alloy containing 0.5 mass%Si become fine, but resulting in no increase of elongation. An addition of 0.5 mass%Ca makes strength high, whereas no sign of the improvement of elongation is recognized. Zr does not show any large difference in the microstructure and tensile strength of the ternary alloys. As a result, there is no significant increase of ductility for the examined alloys although the recrystallized grain size is reduced as compared with the ternary alloys.
軽金属 47(4), 202-207, 1997-04-30
The Japan Institute of Light Metals