含Mo單晶鎳基合金的高溫蠕變及損傷行為

含Mo單晶鎳基合金的高溫蠕變及損傷行為Creep and damage behavior of containing Mo nickel-based single crystal superalloy at high temperature

通過蠕變性能測試及組織形貌觀察，研究含3%和5%(質(zhì)量分?jǐn)?shù))Mo無Re單晶鎳基合金的高溫蠕變和損傷行為。結(jié)果表明：與3%Mo單晶合金相比，5%Mo無Re單晶合金具有較好的蠕變抗力和較長的蠕變壽命，測定出5%Mo單晶合金在1040 ℃、137 MPa的蠕變壽命為556 h。在施加的溫度和應(yīng)力范圍內(nèi)，測定出合金在穩(wěn)態(tài)蠕變期間的表觀蠕變激活能Q=484.7 kJ/mol。合金在穩(wěn)態(tài)蠕變期間的變形機(jī)制是位錯在基體中滑移和攀移越過筏狀γ′相；合金在蠕變較后階段的變形機(jī)制是位錯剪切進(jìn)入筏狀γ′相。隨蠕變進(jìn)行，位錯的交替滑移致使合金中筏狀γ′相發(fā)生扭曲，并在筏狀γ′/γ兩相界面發(fā)生裂紋的萌生和擴(kuò)展，直至斷裂，是合金在高溫蠕變后期的損傷與斷裂機(jī)制。

By means of creep property measurement and microstructure observation, the creep and damage behaviors of containing 3% and 5% (mass fraction) Mo single crystal Ni-based superalloy at high temperature were investigated. The results show that, compared to 3%Mo single crystal superalloy, the 5%Mo superalloy displays a better creep resistance and longer creep life, the creep life of alloy at 1040 ℃ and 137 MPa is measured to be 556 h. The deformation mechanisms of the alloy during steady state creep are dislocation slipping in γ matrix and climbing over the rafted γ? phase. In the later stage of creep, the deformation mechanism of alloy is dislocation shearing into the rafted γ? phase. As the creep going on, the alternate activation of dislocations slipping resulted in the twisted of rafted γ? phase promotes the initiation and propagation of crack occurring in the interface of γ/γ? phase, until fracture, which is thought to be the damage and fracture mechanism of alloy during creep at high temperature.

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