摘要
相组成和结构对于黏结层合金的抗高温氧化性能起着重要作用,而合金的抗高温氧化性能又直接影响其制备的热障涂层的服役性能与工作寿命。采用Thermo-Calc热力学计算、X射线衍射仪、场发射扫描电镜等分析手段研究不同Hf含量对NiCoCrAlY黏结层合金相组成和结构、1150℃等温氧化过程及Hf等元素分布特征的影响。热力学理论计算及室温组织观察结果表明,含0.5%(质量分数,下同)和1%Hf的黏结层合金相组成均以FCC_L12结构的γ′-Ni_(3)Al相与BCC_B2结构的β-NiAl相为主。Hf含量由0.5%增加到1%后,合金的液相线温度由1422℃降低为1418℃,固相线温度从1297℃降低至1287℃,凝固区间温度增加,α-Cr相析出温度由860℃提高到880℃,1000~1250℃温度范围内含0.5%Hf的黏结合金β-NiAl相含量高于1.0%Hf。不同Hf含量黏结层合金200 h等温氧化分析结果表明,氧化增重量与氧化时间曲线均符合典型抛物线氧化动力学规律。随着合金中Hf含量由0.5%增加到1.0%,合金的平均氧化速率由(0.15±0.008)g·m^(-2)·h^(-1)增加到(0.32±0.006)g·m^(-2)·h^(-1),拟合的抛物线氧化速率常数k_(p)则由4.163 g^(2)·m^(-4)·h^(-1)增加到9.337 g^(2)·m^(-4)·h^(-1)。氧化物相及形貌分析表明:氧化后合金表面主要由致密的Al_(2)O_(3)组成;由合金截面观察到深灰色衬度的Al_(2)O_(3)膜,氧化膜中还分布着白色衬度的HfO_(2)相,且随着Hf含量上升,氧化膜中分布着的HfO_(2)由不连续的点状分布转变为长条形的连续分布,内氧化的HfO_(2)颗粒数量与面积增加,贫Al层的厚度也大大提升。
The phase composition and structure play an important role in the high-temperature oxidation resistance of the bonding layer alloy.Furthermore,the high-temperature oxidation resistance of the alloy strongly affects the working life of the thermal barrier coating prepared.In this paper,the effects of different Hf contents on the phase composition,structure,and isothermal oxidation process at 1150℃ are investigated by Thermo-Calc,X ray diffraction,and field emission scanning electron microscopy.The results of theoretical calculations and microstructure observations indicate that the phase composition of NiCoCrAlY alloy containing 0.5%(mass fraction,the same below)and 1% Hf are mainly composed of the γ′-Ni_(3)Al phase and the β-NiAl phase.As the Hf content increases from 0.5%to 1%,the liquidus temperature of the alloys decreases from 1422℃to 1418℃,the solidus temperature decreases from 1297℃ to 1287℃,and the solidification temperature range increases.Furthermore,the precipitation temperature of the α-Cr phase increases from 860℃ to 880℃ with increasing Hf content.The β-NiAl phase content of the bonding alloy with 0.5%Hf in the temperature range of 1000-1250℃ is higher than that of the alloy with 1.0% Hf.The isothermal oxidation analysis for 200 h shows that the mass gain versus oxidation time curves follow the typical parabolic oxidation kinetics.As the Hf content increases from 0.5% to 1.0% in alloys,the average oxidation rate increases from(0.15±0.008)g·m^(-2)·h^(-1)to(0.32±0.006)g·m^(-2)·h^(-1),and the parabolic oxidation rate constant k_(p)increases from 4.163 g^(2)·m^(-4)·h^(-1)to 9.337 g^(2)·m^(-4)·h^(-1).According to the phase analysis and morphology observation of the oxide layer,it is found that the oxide layer is mainly a dense Al_(2)O_(3) layer;the white contrast HfO_(2) phase is also distributed in the oxide film.With the increase of Hf content,the distribution of the HfO_(2) phase in the oxide layer changes from discontinuity to continuousness,and the number and area of HfO_(2) particles increase.Meanwhile,the internal oxidation degree is aggravated and the thickness of the lean Al layer is improved.
作者
薛瑞
张婧
辛文彬
宋希文
常振东
牟仁德
蔡妍
XUE Rui;ZHANG Jing;XIN Wenbin;SONG Xiwen;CHANG Zhendong;MU Rende;CAI Yan(College of Rare Earth Industry(College of Rare Earth Engineering Technology),Inner Mongolia University of Science and Technology,Baotou 014010,Inner Mongolia,China;Key Laboratory of Green Extraction&Efficient Utilization of Light Rare-Earth Resources(Ministry of Education),Inner Mongolia University of Science and Technology,Baotou 014010,Inner Mongolia,China;AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China)
出处
《材料工程》
北大核心
2025年第6期24-34,共11页
Journal of Materials Engineering
基金
国家科技重大专项项目(J2019-Ⅶ-0010-0150)
中央引导地方科技发展资金项目(2023ZY0009)
中国航发北京航空材料研究院院基金(KJ42250521)
内蒙古自治区高等学校青年科技英才支持计划(NJYT24070)
内蒙古自治区教育厅一流学科科研专项(YLXKZXNKD-050)
内蒙古自治区直属高校基本科研业务费(118)。
