(1. 蘇州大學(xué) 機電工程學(xué)院，蘇州 215006； 2. 武漢理工大學(xué) 材料復(fù)合新技術(shù)國家重點實驗室，武漢 430070)
摘 要: 為提高Ti6Al4V合金的高溫抗氧化性能，以Ni80Cr20-40Al-20Si(質(zhì)量分?jǐn)?shù)，%)復(fù)合合金粉末為原料，采用激光熔覆技術(shù)，在Ti6Al4V合金表面制備復(fù)合涂層，系統(tǒng)地分析涂層的物相、顯微組織結(jié)構(gòu)及高溫抗氧化性能。結(jié)果表明：復(fù)合涂層中沒有發(fā)現(xiàn)裂紋，僅有少量氣孔，且與基體實現(xiàn)良好的冶金結(jié)合；Ti5Si3/Al3Ni2作為增強相均勻分布于基體Al3Ti/NiTi中；經(jīng)恒溫800 ℃氧化32 h后，復(fù)合涂層的氧化膜主要由Al2O3和NiO組成，結(jié)構(gòu)連續(xù)致密，氧化動力學(xué)曲線近似符合拋物線規(guī)律，表現(xiàn)出較好的高溫抗氧化性能；而Ti6Al4V合金的氧化膜主要為疏松的TiO2，表面氧化嚴(yán)重，表現(xiàn)出較差的抗氧化性能。激光熔覆NiCrAlSi復(fù)合涂層可望成為有效提高Ti6Al4V合金高溫抗氧化性能的途徑之一。
關(guān)鍵字: 激光熔覆；復(fù)合涂層；顯微組織；高溫氧化
（1. School of Mechanical and Electric Engineering, Soochow University, Suzhou 215006, China; 2. State Key Laboratory of Advanced Technology for Materials Synthesis Processing, Wuhan University of Technology, Wuhan 430070, China）
Abstract:In order to enhance the high-temperature oxidation resistance of Ti6Al4V alloy, Ni80Cr20-40Al-20Si (mass fraction, %) precursor mixed powders were adopted to prepare the protective composite coating on Ti6Al4V alloy by laser cladding. The phase compositions, microstructure and high temperature oxidation resistance of the composite coating were investigated, and the corresponding mechanisms were discussed. The results indicate that the coating which has metallurgical bonding with the substrate, has few pores, and is crack free, and mainly consists of primary Ti5Si3/Al3Ni2 reinforced particles and the inter-primary Al3Ti/NiTi intermetallic compounds matrix. The composite coating can form dense oxide scale consisting of Al2O3 and NiO on the surface, the oxidation dynamic curve is approaching parabolic, indicating good high-temperature oxidation resistance, after isothermal oxidation test at 800 ℃ for 32 h. While the Ti6Al4V alloy is oxidized severely because of the high affinity of Ti atoms to O atoms and the non-protective oxide scales of TiO2. Laser cladding NiCrAlSi composite coating is a promising way to improve the oxidation resistance of Ti6Al4V alloy.
Key words: laser cladding; composite coating; microstructure; high temperature oxidation
