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Papers trace Sc and heat treatment process of Al-Zn-Mg-Cu-Zr Alloy using metallographic observation , scanning electron microscopy and transmission electron microscopy , and tensile the experimental alloy microstructure , phase composition and alloy elements Sc, Zr role analysis , three kinds of heat treatment process of alloy mechanical properties . The results showed that : 1 , add 0.3wt% Sc of 3 # alloy Al - 7.60Zn - 2.30Mg - 1.30Cu - 0.15Zr , Sc and Zr precipitates in the solidification process nascent Al 3 (Sc, Zr) phase particles , which played the role of the non - homogeneous nucleation phase particles , so that 3 # cast microstructures obvious refinement , uniform grain size , grain size in the 20-30μm. 2, Al-7.60Zn-2.30Mg-1.30Cu-0.30Sc-0.15Zr of 3 # alloy precipitates in the homogenization heat treatment process secondary Al 3 (Sc Zr ) phase particles , the phase particles strongly nail dislocations and grain boundaries hinder the growth of grain boundary migration and subgrain improve alloy recrystallization temperature . 3 Add 0.3wt% Sc 3 # < / sup> the alloy 470 ℃ × 2h solid solution water quenched at room temperature and treated with T6 (120 ℃ × 24h) , the tensile strength of the alloy than Al - 7.20Zn - 1.90Mg-1.26Cu-0.13Zr 1 # alloy average increase 65MPa, the average increase in yield strength of 67MPa, elongation increased by an average of 1.0% . 4 , under the experimental conditions of the aging system T6 (120 ℃ × 24h) , containing 0.16wt% Sc Al-7.50Zn-2.11Mg-1.28Cu-0.16Zr 2 # alloy comprehensive mechanical the best performance of the solid solution system to 470 ℃ × 2h. 5 , the analysis of a single-stage aging (T6), 2 # alloy mechanical properties affect the results show that three aging treatment of the two-stage aging (T76 or T73) and three aging (RRA) , 2 # best alloy mechanical properties , its strength and ductility for the σ b = 643 MPa , σ 0.2 = 577MPa , δ = 10.7 % , and its heat treatment The system of 470 ℃ × 120min solid solution , water quench ; 120 ℃ × 24h aging (T6).
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