本研究針對高鋁與鈧含量之LAZ1151與LAZ11101鎂鋰合金進行探討。結果顯示鋁元素的添加有助於提升合金之最大抗拉強度，但也會大幅降低合金之延展性；鈧的添加對於鑄造材有顯著細化晶粒的效果。同時鋁與鈧的添加會促使θ相與α相的析出。 本研究對兩種合金鑄造材進行三和六個月的自然時效觀察結果發現有典型室溫軟化現象，歸咎於β相基材的晶粒成長以及α相的析出；θ相與AlLi相在鑄造材中並未顯現強化的效果。 本研究嘗試利用30%、60%和90%冷輥軋之方法改善合金之強度，LAZ1151與LAZ11101經90%輥軋後強度提升至180 MPa與209 MPa。LAZ11101加工硬化效果較LAZ1151高，可能是由於較高鋁與鈧元素的添加。合金經90%輥軋後室溫軟化的程度較未輥軋之試片緩和，但冷輥軋不能完全抑止合金之α相在室溫下的析出。 本實驗將兩種合金做430℃、1小時之固溶處理後進行自然時效觀察，實驗顯示高鋁與鈧的添加會促使θ相與α相加速析出；析出硬化歸功於θ相的析出，LAZ1151在時效3小時後即到達尖峰時效，LAZ11101則因未固溶成單一過飽和β相而使尖峰時效延遲至12小時。兩種鎂鋰合金固溶處理後，硬度值約為90%輥軋後的兩倍，固溶強化效果遠大於加工硬化效果，此現象歸功於高鋁元素的添加。 The effects of high aluminum (Al) and scandium (Sc) additions on magnesium-lithium alloys were investigated. The alloys of interest are LAZ1151 and LAZ11101. Results indicated that high Al additions could increase the alloys’ strength but also greatly reduced the alloys’ ductility. Adding Sc to the casted alloys had obvious grain refining effects. High Al and Sc additions also increased θ and α phase precipitations. Three and six month natural aging of the casted alloys had been carried out. Room temperature softening phenomenon had been observed, which was probably due to grain growth of the β phase matrix and α phase precipitations. θ phase and AlLi phase showed no strengthening effects on the alloys. 30%, 60% and 90% cold rolling were tried in hopes of improving the alloys’ strength. The tensile strength of LAZ1151 and LAZ11101 increased to a value of 180 MPa and 209 MPa, respectively after 90% cold rolling. Strain hardening effects was higher for LAZ11101 probably because of its higher Al and Sc contents. In addition, 90% cold rolling couldn’t completely impede α phase precipitations under room temperature. The alloys were solid solution treated at 430℃ for 1 hr and then aged under room temperature. Precipitation hardening was mainly due to the precipitation of θ phase. Results showed that high Al and Sc additions could accelerate θ phase and α phase precipitations. LAZ1151 reached peak aging in merely 3 hrs while LAZ11101 delayed till 12 hrs probably due to its deficient solid solubility. The hardness of the solution treated specimens increased nearly two times compared to the cold rolled specimens; showing that solid solution strengthening was much more effective than strain hardening strengthening, which was also a result of high Al additions.
