摘要：DZ444合金是中科院金属研究所在工业重型燃机涡轮工作叶片材料—K444合金的基础上，通过成分微调、定向凝固结晶以及热处理工艺调控等技术创新，生产的一种高品质定向凝固高温合金。本文采用马弗炉对DZ444合金材料进行820℃和920℃高温氧化处理，并通过X射线衍射（XRD）和带能谱的扫描电镜（SEM/EDS）对氧化不同时间后的氧化试样进行分析，来探查定向凝固DZ444合金高温氧化行为。结果表明：添加的元素在金属的表面形成了多种氧化物，其中最主要的是Cr2O3。除此之外，还形成了Al2O3、CoO2、TaO2、TiO2等氧化物。通过扫描电镜观察，金属表面形成了连续且致密的氧化膜，主要是Cr2O3。同时还观察到一些随机分布的氧化物颗粒，结合X射线和能谱可以得出，这些氧化物颗粒主要是TaO2，TiO2，CoO2，WO3是其元素分布不均匀和扩散速度不同导致的。这些氧化物比较松散，颗粒粗糙且大，易开裂和剥落。截面形貌可以看出，DZ444合金氧化时发生了外氧化和内氧化现象，外层主要为连续且致密的氧化物Cr2O3，内层主要是Al2O3，它会在内部产生楔状氧化物，产生“钉扎作用”，使氧化膜与基体结合的更加牢固。87905

毕业论文关键词：DZ444合金；定向凝固；定向凝固高温合金；高温氧化

Study on the oxidation behavior of a directional solidification alloy at high temperature

Abstract：DZ444 alloy is the foundation of CAS Institute of metal research, industrial gas turbine blade materials, K444 alloy, directional solidification, by adjusting the composition of crystallization and heat treatment process control technology innovation, to develop a high performance and low cost of directionally solidified superalloy。This paper adopts a muffle furnace for 820 degrees and 920 degrees high temperature oxidation treatment of DZ444 alloy material, and through X ray diffraction (XRD) and scanning electron microscopy with energy spectrum (SEM/EDS) of oxidized specimens at different oxidation time was analyzed。 To study the effect of high temperature oxidation behavior of DZ444 alloy of various elements。The results showed that the addition of elements formed a variety of oxides on the surface of the metal, the most important of which was Cr2O3。In addition, Al2O3,CoO2,TaO2,TiO2 and other oxides have been formed。 It is observed by scanning electron microscopy that a continuous and dense oxide film is formed on the surface of the metal, mainly Cr2O3。At the same time, some randomly distributed oxide particles were observed。 Combined with X ray and energy spectrum, it can be concluded that these oxide particles are mainly TaO2, TiO2, CoO2 ,WO3,which are caused by uneven distribution of elements and diffusing speed。These oxides are loose, coarse and easy to crack and exfoliate。 Cross section morphology can be seen, the oxidation and internal oxidation of DZ444 alloy oxidation occurs when the outer layer is mainly for continuous and dense oxide layer is mainly Cr2O3, Al2O3, it will form a wedge-shaped oxide inside, "pinning effect", the oxide film and the substrate with a more solid。

Key words: DZ444 alloy; directional solidification; directionally solidified superalloy; high temperature oxidation

目录

1 绪论 1源-于,优Y尔O论U文.网wwW.youeRw.com 原文+QQ75201,8766

1。1 高温合金 1

1。2 高温合金的应用及性能要求 2

1。3 定向凝固高温合金 2

1。4 高温氧化的热力学与动力学原理 3

1。5 氧化的动力学规律原理 4

1。6 研究目的及意义