含鉿高鎢K416B鎳基鑄造高溫合金的組織與蠕變行為Microstructure and creep behavior of Hf-containing K416B as-cast Ni-based superalloy with high W content

通過組織形貌觀察和蠕變性能測試，研究了含鉿高鎢K416B鎳基鑄造合金的組織及蠕變機(jī)制。結(jié)果表明：合金鑄態(tài)組織由γ基體、γ?相、MC和M₆C型碳化物組成；其中，MC碳化物主要以鏈狀和漢字型結(jié)構(gòu)分別在晶界和枝晶間析出，而大塊狀M₆C碳化物鑲嵌在共晶處；蠕變期間，合金的變形機(jī)制是位錯在基體中可沿不同方向發(fā)生滑移，且位錯可繞過或剪切γ′相；蠕變后期，高密度位錯在碳化物和晶界處塞積，產(chǎn)生應(yīng)力集中，致使裂紋沿晶界和碳化物/共晶界面處萌生及擴(kuò)展是合金的斷裂機(jī)制。

By means of microstructure observation and creep property measurement, the microstructure and creep mechanism of Hf-containing K416B 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 M₆C carbides. Thereinto, the MC carbide with chain-like structure and Chinese script precipitates, in the grain boundaries and inter-dendrite, respectively. And the blocky M₆C 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.

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