Microstructure of as-cast billet and homogenization treatment of 2A70 heat-resistance aluminum alloy

Abstract:

The microstructure of casting billet and the homogenization treatment were investigated by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD) respectively. Meanwhile, using the Thermo-Calc software, the solidification path for the Al-2.4Cu-1.5 Mg-1.1Fe-1.1Ni alloy was calculated. On this basis, the phases precipitated during solidification were analyzed and the transition temperature of the non-equilibrium eutectic phases was also calculated, which provided a theoretical basis for the research on microstructure and homogenization process. According to the calculated results, the α-Al、Al2CuMg、Al2Cu、Al9FeNi、Al7Cu4Ni and Al7Cu2Fe phases are exist in the 2A70 alloy, which in accordance with the experimental findings. In addition, the transition temperature for the non-equilibrium eutectic phases can be approximate substituted by the computed data. The reasonable homogenization treatment process for the investigated alloy is 490℃?2~16h 520℃?2h. During the high-temperature and long-time homogenization process, the non-equilibrium eutectic phases are dissolved completely and the Al9FeNi、Al7Cu4Ni and Al7Cu2Fe changes a little.

Key words:heat-resistance aluminum alloy, thermodynamic calculation, homogenization treatment