含铪高钨K416B镍基铸造高温合金的组织与蠕变行为

Microstructure and creep behavior of Hf-containing K416B as-cast Ni-based superalloy with high W content

通过组织形貌观察和蠕变性能测试,研究了含铪高钨K416B镍基铸造合金的组织及蠕变机制。结果表明:合金铸态组织由γ基体、γ'相、MC和M6C型碳化物组成;其中,MC碳化物主要以链状和汉字型结构分别在晶界和枝晶间析出,而大块状M6C碳化物镶嵌在共晶处;蠕变期间,合金的变形机制是位错在基体中可沿不同方向发生滑移,且位错可绕过或剪切γ′相;蠕变后期,高密度位错在碳化物和晶界处塞积,产生应力集中,致使裂纹沿晶界和碳化物/共晶界面处萌生及扩展是合金的断裂机制。

By means of microstructure observation and creep property measurement, the microstructure and creep mechanism of Hf-containing K416 B as-cast Ni-based superalloy with high W content were investigated. The results show that the as-cast microstructure of the alloy consists of γ matrix, γ＇phase, MC and M6 C carbides. Thereinto, the MC carbide with chain-like structure and Chinese script precipitates, in the grain boundaries and inter-dendrite, respectively. And the blocky M6 C carbide embeds in the eutectic. During creep, the deformation mechanisms of the alloy are that the dislocations with different orientations slip in the matrix, and the dislocation may bypass or shear into γ＇ phase. In the late stage of creep, high density dislocations may pile up near the carbides or boundaries, and the fact may induce the stress concentration to cause the crack initiating and propagating along the grain boundaries and the interface between the carbide and eutectic, which is considered to be the fracture mechanism of the alloy.