2D70耐热铝合金显微组织均匀化热处理

Homogenization treatment and microstructure of semicontinous casting ingot of 2D70 heat-resistance aluminum alloy

利用光学显微镜、扫描电子显微镜、能谱分析、差示扫描量热、X射线物相分析研究2D70耐热铝合金半连续铸锭的结晶相及合理的均匀化热处理制度。结果表明:合金半连续铸锭中枝晶偏析严重,存在大量非平衡共晶相,其成分为α(Al)+θ(Al2Cu)+S(Al2CuMg),其初始熔化温度为505.4℃;在530℃温度以下进行均匀化时,合金中的难溶相Al7Cu2Fe、Al7Cu4Ni、Al9FeNi含量基本没有变化;合金合理的均匀化热处理制度为(490℃,16 h)+(520℃,16 h)。

The constituents of the semicontinuous casting ingot of 2D70 heat-resistance aluminum alloy and homogenization treatment were studied by optical microscopy（OM）,scanning electron microscopy with energy dispersive X-ray spectroscopy（SEM-EDX）,differential scanning calorimetry（DSC） and X-ray diffraction analysis（XRD）.The results indicate that the semicontinuous casting ingot of 2D70 aluminum alloy presents a dendritic microstructure with severe segregation.The phases of the nonequilibrium eutectic are α（Al）＋ θ（Al2Cu） ＋S（Al2CuMg） whose overheating temperature is 505.4 ℃.The volume fraction of hard dissolve phases such as Al7Cu2Fe,Al7Cu4Ni and Al9FeNi changes a little below 530 ℃.The reasonable homogenization treatment process of the alloy is（490 ℃,16 h） ＋（520 ℃,16 h）.