镍基高温合金GH4282的凝固和偏析行为

Solidification and segregation behavior of nickel-based superalloy GH4282

摘要:

采用差示扫描量热（DSC）分析、显微组织观察和热力学计算相结合的方法对镍基高温合金GH4282的凝固过程和元素偏析行为进行研究，得到了合金的凝固顺序以及元素偏析特征。结果表明，GH4282合金的凝固顺序为：γ基体、MC碳化物以及少量的硼化物。由DSC测得的合金GH4282合金的固-液相温度范围为1316~1367 ℃，MC、M6C型碳化物和γ′相的溶解温度分别为1338 ℃、1092 ℃和1003 ℃。热力学计算结果表明，GH4282合金在凝固过程C、B、Ti和Mo偏聚于枝晶间，Al偏析于枝晶干，Cr、Fe和Co几乎不发生偏析，这与铸态组织观察到的元素偏析特征是一致的。

Abstract:

The solidification process and the segregation behavior of the elements of GH4282 superalloy were investigated by a combination of differential scanning calorimeter (DSC), microstructure observation and thermodynamic calculation. The solidification sequence and the characteristics of elements segregation were obtained. The results show that the solidification sequence of GH4282 is as follows: γ matrix, MC carbide and a small amount of boride. The solidus-liquidus temperature range determined by DSC is 1316~1367 ℃. The measured solvus temperature of MC carbide, M6C carbide and γ′ phase is 1338 ℃, 1092 ℃and 1003 ℃, respectively. Thermodynamic calculations show that C, B, Ti and Mo segregate to the interdendritic regions, while Al segregates to the dendrite cores. Cr, Fe and Co do not exhibit any significant tendency to segregate to either the interdendritic region or the dendrite core during the solidification process of GH4282 superalloy. These results about segregation behavior of the elements agree well with those observed by as-cast microstructure observation.