(1. 湖南工程學(xué)院 機(jī)械工程學(xué)院，湘潭 411101；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用電弧離子鍍(AIP)在Ti-6.48Al-0.99Mo-0.91Fe(質(zhì)量分?jǐn)?shù)，%)鈦合金表面制備Ta-10W(質(zhì)量分?jǐn)?shù)，%)涂層。通過(guò)掃描電鏡(SEM)與能譜(EDS)分析、透射電鏡(TEM)分析、電子探針?lè)治?EPMA)，X衍射分析(XRD)，劃痕及納米壓痕試驗(yàn)，研究鈦合金基體與Ta-W涂層經(jīng)900 ℃大氣循環(huán)氧化前后的物相組成、組織形貌及性能，討論涂層/基體的氧化行為。結(jié)果表明：沉積態(tài)Ta-W涂層連續(xù)、均勻、致密，由顆粒細(xì)小(≤50 nm)的α-Ta(W)堆積成100~250 nm的等軸晶組成，硬度為14.4~15 GPa，與基體的臨界載荷為58.5 N；經(jīng)900 ℃大氣循環(huán)氧化后，鈦合金表面形成帶裂隙的層狀TiO2、Al2O3疏松混合氧化膜，氧化膜明顯脫落；Ta-W涂層能明顯提高鈦合金的抗循環(huán)氧化性能，形成以β-Ta2O5為主的致密氧化膜；隨著氧化的進(jìn)行，氧化膜中TiO2、Al2O3含量增加并出現(xiàn)AlTaO4、AlWO4相，氧化膜始終保持完整；氧化過(guò)程中，基體中Ti、Al元素及涂層中Ta、W元素互擴(kuò)散，在界面形成AlTa2、Al2Ta3、Al3Ti、TixW1-x相，O元素?cái)U(kuò)散并固溶于基體，在近界面基體處形成厚度逐漸增加的富Ta、W、Al、O、α-Ti固溶體(穩(wěn)定)區(qū)，涂層元素向氧化膜和基體擴(kuò)散而被消耗為其失效的主要原因。
關(guān)鍵字: Ta-W涂層；鈦合金；循環(huán)氧化；元素?cái)U(kuò)散
（1. School of Mechanical Engineering, Hunan Institute of Engineering, Xiangtan 411101, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Ta-10W (mass fraction, %) coating was deposited on Ti-6.48Al-0.99Mo-0.91Fe (mass fraction, %) titanium alloy by arc ion plating (AIP). Scratch test, nano indentation test, SEM, EDS, TEM, EPMA and XRD analysis were carried out to study the phase composition, microstructure and properties of the substrate and coating before and after cyclic oxidation at 900 ℃ in air. The oxidation behavior of the coating/substrate was discussed. The results show that the as-deposited Ta-W coating is continuous, uniform and compact with fine α-Ta(W) particles (≤50 nm) aggregating to form 100-250 nm equiaxed grains. The coating with hardness of 14.4-15 GPa and critical load of 58.5 N is obtained from the scratch test. Laminar Al2O3 and TiO2 mixed scale with fissuring is formed and desquamated obviously on the substrate after cyclic oxidation at 900 ℃ in air. Ta-W coating can evidently improve the cyclic oxidation resistance of the substrate. An integrity and compact scale, which is mainly made up of β-Ta2O5, formed on Ta-W coating. With the oxidation going on, the contents of TiO2, Al2O3, AlTaO4 and AlWO4 in the scale increase. The coating elements (Ta and W) and substrate elements (Ti and Al) interdiffuse during the oxidation. AlTa2, Al2Ta3, Al3Ti, TixW1-x phases form on the interface. With the diffusion of Ta, W, Ti, Al and O, α-Ti solid solution layer (stabilized layer) forms in the substrate near the interface. The degradation of Ta-W coating mainly attributes to the consumption of coating elements to form scale and dissolve in the substrate.
Key words: Ta-W coating; titanium alloy; cyclic oxidation; element diffusion
