Microstructure evolution of a high alloying Al-9Zn-2Mg-2Cu-0.3Ce alloy during homogenization

doi:10.13251/j.issn.0254-6051.2021.09.034

Abstract

Abstract: As-cast microstructure and microstructure evolution during homogenization of highly alloying Al-9Zn-2.0Mg-2Cu-0.3Ce alloy were studied by means of optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD) and differential scanning calorimeter (DSC), and a rather optimal single-stage homogenization process was obtained. The results show that in the as-cast alloy, the dendrite network is well developed with serious segregations of Zn, Mg and Cu, and the main non-equilibrium solidification phases are T(AlZnMgCu) phase and θ(Al₂Cu) phase. After homogenization heat treatment at 470 ℃ for 48 h, the dendrite network in the alloy is basically eliminated and the solidification phase T gradually dissolves into the matrix. The main residual phases are high temperature resistant phases Al₂CuMg, Al₈Cu₄Ce and Al₇Cu₂Fe. Diffusion kinetic analysis shows that the single-stage homogenization process of annealing at 470 ℃ for 48 h is sufficient to make the non-equilibrium phase in the alloy to re-dissolve into the matrix.

Key words: Al-Zn-Mg-Cu alloy, Ce, homogenization, microstructure

CLC Number:

TG146.2

Zhang Qian, Shi Dandan, Li Caiqiong, Zhao Zhiguo, Shi Xianli. Microstructure evolution of a high alloying Al-9Zn-2Mg-2Cu-0.3Ce alloy during homogenization[J]. Heat Treatment of Metals, 2021, 46(9): 187-192.

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