(北京航空材料研究院先进高温结构材料重点实验室，北京 100095)
摘 要: 对完全热处理后的第二代单晶高温合金DD6分别在1100、1150、1200、1250、1300和1320 ℃温度下保温1 h后再进行空冷处理。用扫描电镜(SEM)分析经不同温度处理后合金的显微组织，通过JMatPro相图计算和差热分析讨论合金的组织演变机理。结果表明：DD6合金在1100、1150和1200 ℃保温处理后，γ′相尺寸稍有增大；1250 ℃保温处理后，γ′相尺寸明显增大，大小分布极不均匀，大部分γ′/γ相界面为锯齿状；1300 ℃保温处理后，少部分未完全回溶的γ′相具有锯齿状的γ′/γ相界面，大部分γ′相回溶后重新析出不规则、细小的γ′相；1320 ℃保温处理后，γ′相完全回溶后重新析出不规则、细小的γ′相。合金经不同温度处理后，γ′相长大或溶解、或重新析出的相大小、形态和体积分数均不相同。在1100 ℃热处理后，合金中γ′相体积分数比完全热处理合金稍有增加；在其他温度下处理后，合金中γ′相体积分数比完全热处理合金的均不同程度地减小。合金完全热处理后和经过1320 ℃保温处理后，基体通道中没有二次γ′相析出；而在1100~1300 ℃热处理后，基体通道中析出细小的二次γ′相。合金在不同温度处理后得到明显不同特征的组织，表明使用温度对合金的组织有显著的影响。
关键字: 单晶高温合金；DD6合金；γ′相；组织演变
（Science and Technology on Advanced High Temperature Structural Materials Laboratory,
Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The second generation single crystal superalloy DD6 after standard heat treatment was heat-treated at 1100, 1150, 1200, 1250, 1300 and 1320 ℃ for 1 h, respectively, and was then air cooled. The microstructures of the alloy heat-treated at different temperatures were investigated by SEM. The microstructure evolution mechanism of the alloy was estimat using JMatPro software and DSC．The results show that the size of γ′ phase slightly increases after DD6 super alloy heat-treatment at 1100, 1150 and 1200 ℃. The size of γ′ phase increases apparently and its size distribution is very uneven after heat treatment at 1250 ℃. The small part of γ′ phase has serrated γ′/γ phase surface as a result of incomplete solution and the irregular small γ′ phase is major after heat-treatment at 1300 ℃. While the irregular small γ′ phase precipitates again, followed complete solution after heat-treatment at 1320 ℃. The size, shape and volume fraction of γ′ phase vary with the heat treatment temperatures because it grows, dissolves or precipitates again. The volume fraction of γ′ phase decreases to different degrees after heat-treatment at different temperatures except 1100 ℃. There is no fine second γ′ phase in the γ matrix channel of the alloy after standard heat-treatment and heat-treatment at 1320 ℃. But the fine second γ′ phase precipitates in the γ matrix channel after heat-treatment at temperature range of 1100-1300 ℃. Different microstructures are obtained after heat-treatment at different temperatures, which indicates that the using temperature has obvious effect on the microstructure of the alloy.
Key words: single crystal superalloy; DD6 alloy; γ′ phase; microstructure evolution
