Microstructure of As-Cast 7085 Aluminum Alloy by Homogenization

Abstract:

7085 aluminum alloy has been widely used in aviation and aerospace because of high fracture toughness, high strength, slow quench sensitivity and low density. In the as-cast microstructure, it is not avoidable for massive un-dissolved secondary phases and dendritic segregation. The microstructure of as-cast high strength 7085 aluminum alloy after two-stage homogenization was studied by optical microscopy (OM), X-ray diffractometer (XRD), scanning election microscopy (SEM), energy dispersive spectrometer (EDS) and differential scanning calorimeter (DSC). It was found that the severe dendritic segregation exists in as-cast 7085 aluminum alloy and a small amount of Al₇Cu₂Fe exists in the as-cast 7085 alloy. The evolution of primary eutectic structure of 7085 alloy consists of three processes: the dissolution of non-equilibrium eutectic phase α (Al) + Mg (Zn)₂, the transformation from Mg (Zn)₂ to Al₂CuMg and the dissolution of new phase Mg (Zn)₂. A suitable two-stage homogenization scheme for as-cast 7085 aluminum alloy is 300°C/8 h + 465°C/24 h.

• Periodical: Materials Science Forum (Volume 898)
• Pages: 265-271
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.898.265
• Online since: June 2017
• Authors: Yue Wen Shao, Yi Liu, Jin Feng Leng*, Kun Zhu, Ze Mei Liu, Chen Xue Li
• Keywords: 7085 Aluminum Alloy, Homogenization Annealing, Microstructure, Precipitated Phase

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