(沈陽工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，沈陽 110870)
摘 要: 通過對一種4.5%Re(質(zhì)量分?jǐn)?shù))鎳基單晶合金進行不同工藝熱處理、蠕變性能測試及組織形貌觀察，研究了固溶時間對該合金組織結(jié)構(gòu)與高溫蠕變行為的影響。結(jié)果表明：鑄態(tài)合金中各元素存在較大的成分偏析，經(jīng)高溫長時間固溶及時效處理后，合金中各元素在枝晶間/臂的偏析程度明顯降低；將固溶時間由10 h延長至24 h后，合金在1100 ℃、137 MPa的蠕變壽命由101 h提高至164 h；其中，10 h固溶處理合金中仍存在較大程度的元素偏析，并且在蠕變期間，析出針狀TCP相。合金在高溫蠕變期間的變形機制是位錯在基體中滑移和剪切筏狀γ′相；蠕變后期，大量位錯剪切筏狀γ′相，致使近斷口區(qū)域的筏狀γ′相扭曲，在筏狀γ/γ′兩相界面發(fā)生裂紋的萌生，并沿垂直于應(yīng)力軸方向擴展，直至發(fā)生蠕變斷裂。這是合金的高溫蠕變斷裂機制。
關(guān)鍵字: 單晶鎳基合金；Re；TCP相；元素偏析；蠕變
（School of Mechanical Engineering, Shenyang University of Chemical Technology, Shenyang 110870, China）
Abstract:By means of heat treatment at different regimes and creep property measurement, combining with microstructure observation, the effects of the solution time on the microstructure and creep behaviors of a 4.5%Re (mass fraction) nickel-based single crystal superalloy at high temperature were investigated. The results show that the segregation extent of the elements in the as-cast alloy may be obviously reduced by means of heat treatment at high temperature. When extended the solution time from 10 h to 24 h, the creep life of the alloy enhances from 101 h to 164 h. Thereinto, bigger segregation extent of the elements appears still in the alloy treated by technique 1, which results in the precipitation of the needle-like TCP phase. The deformation mechanism of the alloy during creep is dislocations slipping in the γ matrix and shearing into the rafted γ′ phase. At the later stage of creep, the significant amount of dislocations shearing into the rafted γ′ phase results in the twist of the rafted γ′ phase, which may promote the initiation and propagation of the micro-cracks at the interfaces of γ/γ′ phases up to the occurrence of creep fracture. This is thought to be the fracture mechanism of alloy during creep at high temperature.
Key words: nickel-base single crystal superalloy; Re; TCP phase; element segregation; creep
