Homogenization process and microstructure evolution of Al-4.5Cu-3.5Zn-0.5Mg as-cast alloy

doi:10.13251/j.issn.0254-6051.2020.01.035

Abstract

Abstract: The microstructure of an as-cast Al-4.5Cu-3.5Zn-0.5Mg alloy and its evolution during different two-step homogenization treatments were studied by means of scanning electron microscope (SEM), electron probe micro-analyzer (EPMA), differential scanning calorimeter (DSC) and optical microscope (OM). The results show that the as-cast microstructure is mainly composed of α-Al and coarse Al ₂ Cu phase with a small amount of AlZnMgCu and Al ₇ Cu ₂ Fe phases, and severe dendritic segregation of alloying elements exists in the alloy ingot. After homogenized at 470 ℃ for 12 h, the AlZnMgCu phase is mainly dissolved into the matrix. The Al ₂ Cu phase is gradually dissolved into the matrix by increasing the second-step homogenization temperature from 490 ℃ to 520 ℃ or prolonging the holding time, and all the alloying elements tend to be homogenized. The over burnt temperature of the alloy is 520 ℃, and the proper homogenization process is 470 ℃×12 h+510 ℃×32 h, which agrees well with the kinetic calculation results of homogenization.

Key words: Al-4.5Cu-3.5Zn-0.5Mg alloy, two-step homogenization, microstructure

CLC Number:

TG146.2

Wang Nanhai, Yi Danqing, Wang Haisheng, Cheng Yong. Homogenization process and microstructure evolution of Al-4.5Cu-3.5Zn-0.5Mg as-cast alloy[J]. HTM, 2020, 45(1): 174-180.

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