Microstructural evolution of 2026 aluminum alloy during homogenization

Abstract

The microstructural evolution of 2026 aluminum alloy during homogenization treatment was investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that severe dendritic segregation exists in the as-cast 2026 alloy and the main secondary phases at grain boundary are S (Al₂CuMg) and θ (Al₂Cu) phases. Elements Cu, Mg and Mn distribute unevenly from grain boundary to the inside of as-cast alloy. With the increase of homogenization temperature or the prolongation of holding time, the residual phases gradually dissolve into the matrix α(Al) and all the elements become more homogenized. According to the results of microstructural evolution, differential scanning calorimetry and X-ray diffraction, the optimum homogenization parameter is at 490 °C for 24 h, which is consistent with the result of homogenization kinetic analysis.

Keywords

2026 aluminum alloy / dendritic segregation / homogenization / microstructure evolution / homogenization kinetics

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