(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；2. 中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083)
摘 要: 采用電弧離子鍍(AIP)技術(shù)在TC4 (Ti-6Al-4V) 鈦合金基體表面沉積制備NiCrAlY涂層，測定TC4鈦合金和NiCrAlY涂層在700~900 ℃的氧化動力學(xué)曲線。通過掃描電鏡(SEM)、能譜(EDS)分析與X射線衍射分析 (XRD)研究TC4鈦合金和NiCrAlY涂層氧化前后物相組成和組織形貌，討論氧化過程中元素的擴(kuò)散行為。結(jié)果表明：在700~900 ℃靜態(tài)空氣中氧化100 h，NiCrAlY涂層能明顯提高TC4鈦合金的抗氧化性能，TC4鈦合金氧化后形成Al2O3層和TiO2層交替出現(xiàn)的氧化膜層；經(jīng)700和800 ℃氧化后，NiCrAlY涂層保持其原始的相組成，但在表面形成Al2O3和Cr2O3混合氧化膜；經(jīng)900 ℃氧化后，氧化膜由Al2O3和TiO2組成；經(jīng)700 ℃氧化時，主要發(fā)生Ti和Ni兩種元素的擴(kuò)散；經(jīng)800和900 ℃氧化時，由于Ti及Ni元素的劇烈擴(kuò)散，界面附近出現(xiàn)Kirkendall疏孔帶和約100 μm的β相穩(wěn)定區(qū)；經(jīng)900 ℃氧化時，Ti擴(kuò)散到涂層表面形成氧化物導(dǎo)致氧化速率提高，Cr元素開始向基體擴(kuò)散并在近界面處富集。
關(guān)鍵字: NiCrAlY涂層；TC4鈦合金；氧化；擴(kuò)散
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;2. Key Laboratory of Nonferrous Metals Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China）
Abstract:The NiCrAlY coating was deposited on TC4 titanium alloy by arc ion plating (AIP). The oxidation kinetic curves of TC4 titanium alloy and NiCrAlY coating were obtained. The microstructures and morphologies of TC4 alloy and NiCrAlY coating before and after oxidation were analyzed by SEM, EDS and XRD, and the elements diffusion behavior was also studied. The results show that the oxidation resistance of TC4 alloy is evidently improved by NiCrAlY coating at 700−900 ℃. The oxidation layer of TC4 consists of TiO2 and Al2O3 layers alternately. After oxidation at 700 and 800 ℃, NiCrAlY coating still contains the original phases and the oxidation produces are made up of Al2O3 and Cr2O3. At 900 ℃, the oxidation coat consists of Al2O3 and TiO2. At 700 ℃, Ti and Ni are the major diffusion elements. Because of the violent diffusion of Ti and Ni, Kirkendal porosity belts and β-stabilizes zones appear near the interface at 800 and 900 ℃. At 900 ℃, Ti diffuses to the coating surface and form TiO2, which increases the oxidation speed. Cr begins to diffuse to the substrate and accumulates at the interface at 900 ℃.
Key words: NiCrAlY coating; TC4 titanium alloy; oxidation; diffusion
