Effects of Sc Addition on Age-hardening and Precipitation Behavior of Al-3.0 % Cu Alloy

Age-hardening and precipitation behaviors of Al-3.0%Cu alloy and Al-3.0%Cu-0.3%Sc alloy at 150,200,250,300,350 and 400 ℃ were investigated by measuring of Vickers-hardness and observation of transmission electron microscopy(TEM). The results indicated that there almost was no difference between Al-Cu-Sc alloy and Al-Cu alloy in age-hardening curves at the temperature below 200 ℃.Al-Cu-Sc alloy had the highest ageing hardness of 90 kN/mm~2 at 300 ℃,6 ks. The effect of Sc on the hardness was most significant at 300 ℃,ΔHV_(max)=45 kN/mm~2.During the ageing of Al-Cu-Sc alloy under the described ageing condition,Al_3Sc and θ′-Al_2Cu precipitated independently without any obvious interaction between them.