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采用差示扫描量热法(DSC)、扫描电镜(SEM)和透射电镜(TEM)系统研究了Ni-Cr-W基高温合金二次M23C6的析出行为。结果表明,合金中二次M23C6的析出温度范围为648～1147℃,当温度高于1160℃时M23C6发生固溶;初生M6C在1349℃发生分解;合金在1400℃时完全熔化。由于时效温度不同,合金中析出两种不同形貌的M23C6。在较低温度时(655～900℃)粗大片层状M23C6在晶界析出;在900℃以上M23C6的形貌由片层状转变为不连续颗粒状。降温速率对M23C6的析出形貌产生一定影响;同时,降温过程中晶界上不连续颗粒状M23C6的析出是导致弯曲晶界形成的主要原因。
The precipitation behavior of secondary M23C6 in Ni-Cr-W superalloy was investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the precipitation temperature range of secondary M23C6 is 648 ~ 1147 ℃. When the temperature is higher than 1160 ℃, M23C6 dissolves. The primary M6C decomposes at 1349 ℃. The alloy melts completely at 1400 ℃. Due to the different aging temperature, two different morphologies of M23C6 were precipitated in the alloy. The coarse lamellar M23C6 precipitates at the grain boundaries at lower temperatures (655-900 ° C). The morphology of M23C6 is transformed from lamellar to discontinuous particles above 900 ° C. The cooling rate has a certain influence on the precipitation morphology of M23C6. Meanwhile, the precipitation of discontinuous granular M23C6 in the grain boundary during the cooling process is the main reason leading to the formation of bent grain boundaries.