Study on the Microstructure and Mechanical Properties of Al-9.0Zn-2.5Mg-2.2Cu-0.2Zr-xSc Aluminum Alloy AITranslate

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Chinese Library Classification Number:TG146.21[金属学及工艺—金属材料]

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High-strength aluminum alloy Al-9.0Zn-2.5Mg-2.2Cu-0.2Zr-xSc was designed,and its as-cast alloy was subjected to homogenizing annealing,hot rolling,solid solution and aging treatments.The reasons for adopting the two-stage homogenizing annealing and its effects on the microstructure of the as-cast alloy were analyzed,and the influence of the solid solution temperature on the microstructure and mechanical properties of the alloy,as well as the Sc content on the mechanical properties of the alloy,were also stu-died.The results show that the use of two-stage homogenizing annealing can not only eliminate the casting stress of the alloy and make the distribution of Zn,Mg and Cu elements more uniform,but also reduce the width of the grain boundary precipitate-free zone(PFZ),which is conducive to the improvement of alloy properties.As the solid solution temperature increases,the degree of recrystallization of the alloy sheet increases,and the number of residual second phases in the alloy decreases.Compared with other solid solution temperatures(450℃,460℃,480℃),the tensile strength of the alloy after solid solution treatment at 470℃for 2 h and aging treatment at 120℃for 24 h is the highest.With the increase of Sc content from 0 to 0.6%,the tensile strength of the alloy first increases and then decreases,and the elongation at break shows a decreasing trend.When the Sc content is 0.42%,the tensile strength of the alloy is the highest.