A201(Al-Cu-Mg-Ag)合金為可熱處理型高強度鋁合金，藉由Ω相及θ’相的析出而達到析出強化的效果。由文獻得知於鋁合金中添加微量稀土元素會產生介金屬化合物，同時成為異質成核點使晶粒產生細化效果，還能提升機械性質及增加合金高溫強度。 故本研究探討添加微量稀土元素La、Ce元素對A201合金之微結構與機械性質之影響。試片經過T7時效處理，利用光學顯微鏡(OM)、掃描式電子顯微鏡(SEM)、微差掃描熱分析儀(DSC)、導電度(%IACS)、硬度試驗、拉伸試驗(Tensile Test)等方法，分析稀土元素的添加對合金微結構的變化與材料機械性質之關係。 結果顯示，A201合金添加稀土元素La及Ce時，於鑄態中會晶出富La相及富Ce相，成為鋁基地異質成核點使晶粒產生細化。經EPMA分析得知富La相及富Ce相的生成消耗合金中Cu、Mg、Ag元素，且無法經由固溶處理回溶於鋁基地內，經T7時效處理後造成Ω及θ’相強化相析出量減少，使得合金硬度及強度降低，但延性提升。 A201(Al-Cu-Mg-Ag) alloy has been widely applied in the aviation and military industries due to its very high mechanical strength and thermal stability which by Ω phase and θ’ phase. Rare earth elements in conventional casting of aluminum alloys have shown beneficial effects on melting and solidification such changes in grain size and precipitation behavior improved the tensile strength at both room and high temperatures. Effect of minor rare earth La and Ce additions on microstructure and mechanical properties of A201(Al-Cu-Mg-Ag) alloys were investigated. After different aging T7, using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Differential Scanning Calorimeter (DSC), Electrical Conductivity Meter (%IACS), Rockwell Hardness Tester and Tensile Test, Analyzing the variation of microstructure of the alloys to compare with the variation of mechanical properties. Experimental results show that addition of La and Ce to A201(Al-Cu-Mg-Ag) alloys produces grain refinement due to the formation of La-rich compounds and Ce-rich compounds during solidification. The formation of La-rich compounds and Ce-rich compounds consumes the parts of Cu、Mg and Ag content, and can’t dissolve in subsequent solution treatment. The available amount of Cu、Mg and Ag which is dissolved in matrix reduces, diminishing the precipitates of Ω and θ’ phase, than the hardness and strength decrease but increase the elongation.
