As-cast Microstructure and Homogenization Treatment of 2A70 Heat-Resistant Aluminum Alloy
The microstructure of cast 2A70 heat-resistant aluminum alloy was analyzed by optical microscopy (OM) and scanning electron microscopy (SEM).Its homogenization treatment was investigated by differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD).Meanwhile,the solidification path for the A1-2.4Cu-1.5Mg-1.1Fe-1.1Ni alloy was calculated using the Thermo-Calc software.Based on the calculation,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,A12CuMg,A12Cu,Al9FeNi,A17Cu4Ni and Al7Cu2Fe phases exist in the 2A70 alloy,which is in accordance with the experimental findings.In addition,the transition temperature for the non-equilibrium eutectic phases can be approximately substituted by the computed data.The reasonable homogenization treatment process for the investigated alloy is 490 ℃/12～16 h+520 ℃/12 h.During the high-temperature and long-time homogenization process,the non-equilibrium eutectic phases are dissolved completely while the Al9FeNi,Al7Cu4Ni and Al7Cu2Fe change little.
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