Re、Ta对第二代定向柱晶合金中初生碳化物形成与分解的影响

Effect of Re and Ta Addition on the Formation and Decomposition of Primary Carbides in a 2nd Generation DS Superalloy

摘要:

采用差热分析（DSC），扫描电镜（SEM），能谱分析（EDS）及X射线衍射（XRD）技术对不同Re、Ta含量的3种合金中MC碳化物的形成与分解进行了研究。结果表明，3种合金的骨架状MC为共晶反应生成，Ta的加入缩小MC中W的含量及不同凝固阶段生成的MC中W含量的差别，促进骨架状MC形成，提高MC形成温度并大幅提高MC的热稳定性。Re不进入MC碳化物，Re的加入可降低MC形成温度并促进μ相从MC周围过饱和的γ基体中析出，进而诱发MC不稳定分解。

Abstract:

The formation and decomposition of MC carbides in alloys with different contents of Re and Ta were investigated by DSC, SEM, EDS and XRD. The results show that script MC carbides in three alloys was formed by eutectic solidification. The addition of Ta not only decreased the W concentration but also minimized the difference of W composition in MC carbides formed at difference freezing period in three alloys. Meanwhile, the addition of Ta also increased the formation temperature and the thermal stability of MC phase significantly. Re was not found in MC carbides. The addition of Re slightly decreased the formation temperature of MC carbides and promoted the precipitation of μ phase from the oversaturated γ matrix.