(沈陽工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，沈陽110870)
摘 要: 通過對有/無元素Re、有/無TCP相合金進行時效處理、持久性能測試及組織形貌觀察，研究TCP相的析出特征以及元素Re、TCP相對合金持久壽命的影響。結(jié)果表明：在時效期間，合金中析出的TCP相在{111}晶面沿＜110＞晶向呈片狀析出，其在(100)晶面具有相互平行或垂直的針狀形貌，在(111)晶面呈現(xiàn)互成60˚角排列的針狀形貌，該TCP相鑒定為µ相。在無Re合金中析出的µ相尺寸較小，在時效期間不發(fā)生球化；而在4.5%Re合金中析出的µ相尺寸較大，且隨時效時間的延長，µ相逐漸粗化并轉(zhuǎn)變成球狀。由于析出的µ相消耗較多的難溶元素，故可明顯降低合金的蠕變抗力和縮短持久壽命。其中，無Re合金2中析出的針狀µ相，在蠕變期間易產(chǎn)生應(yīng)力集中，并促使其發(fā)生裂紋萌生和擴展，是較大幅度縮短合金持久壽命的主要原因；在4.5%Re合金中形成的球狀µ相，在蠕變期間不易產(chǎn)生應(yīng)力集中，是使合金持久壽命縮短幅度減小的主要原因。
關(guān)鍵字: 鎳基單晶合金；時效；TCP相；球化；持久壽命
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:By means of measurement of the stress rupture property and microstructure observation, an investigation was made on the features of TCP phase precipitated and the influence of element Re and TCP phase on the stress rupture property of the single crystal nickel-based superalloys. The results show that during aging, TCP phase is precipitated along the ＜110＞ orientation on {111} planes in the form of the slice-like structure. Thereinto, TCP phase displays a strip-like morphology, arranging in the upright each other on the {100} planes, or arranging at an angle of 60˚ each other on the {111} planes, and the TCP phase is identified as μ phase. The μ phase precipitated in the free-Re alloy is shorter in size, and no feature of the spheroidization is detected during the aging. But the μ phase precipitated in the 4.5%Re alloy displays a longer size, and the coarsening occurs as the aged time prolongs, and then μ phase is gradually transformed into the sphere-like morphology. The precipitated TCP phase may obvious decrease the creep resistance and stress rupture lifetimes of the superalloys due to the consumption of the refractory elements. Thereinto, the stress concentration is easily generated in the regions near the strip-like μ phase in the free-Re alloy, and promotes the initiation and propagation of the cracks during creeping, which is a maim reason reducing the stress rupture lifetimes of the alloy a great extent. And the stress concentration is not easily generated in the regions near the sphere-like μ phase in 4.5%Re alloy, which is a main reason reducing the stress rupture lifetimes of the alloy a small extent.
Key words: single crystal nickel-based superalloy; ageing; TCP phase; spheroidization; stress rupture lifetime
