摘要:NiAl是长程有序的金属间化合物，具有很好的高温抗氧化性能，密度低熔点高等优良性质。但是由于其高温强度和室温塑性差等缺点，所以限制了其广泛应用。为了解决NiAl基合金的这些缺点，采用定向凝固的方法将Cr和Mo元素和稀土元素Hf、Ho添加到NiAl基合金中。NiAl-34Cr-4。3Mo-0。1Hf-0。05Ho共晶合金在820~920℃的高温下发生氧化。采用X射线衍射（XRD）和扫描电镜(SEM)等测试手段研究表明，表面氧化膜主要是Al2O3，Cr2O3和HfO2，Cr和Mo元素的加入会对合金的高温强度和室温塑性得到明显提高，但是对其高温抗氧化性能会稍有不利；加入稀土元素Hf和Ho后会提高氧化膜的力学性能和粘附性，减轻了氧化膜的剥落现象；氧化过程中存在从θ-Al2O3到α-Al2O3的相变和氧的内氧化现象。82417

毕业论文关键词： 金属间化合物；NiAl；高温氧化

Effect of alloying elements on high temperature oxidation behavior of NiAl - based eutectic alloy

Abstract:NiAl is a long-range ordered intermetallic compound, with good high temperature oxidation resistance, low density and low melting point of high quality。 But because of its high temperature strength and poor plasticity at room temperature and other shortcomings, so limited its wide range of applications。 In order to solve these shortcomings of NiAl-based alloys, Cr and Mo elements and rare earth elements Hf, Ho were added to NiAl-based alloys by directional solidification。 NiAl-34Cr-4。3Mo-0。1Hf-0。05Ho eutectic alloy is oxidized at high temperature of 820-920 ℃。 The results show that the surface oxide film is mainly composed of Al2O3, Cr2O3 and HfO2。 The addition of Cr and Mo elements can improve the high temperature strength and room temperature plasticity of the alloy。 However, the addition of Cr and Mo elements in the surface oxide film is improved by X - ray diffraction (XRD) and scanning electron microscopy (SEM) The addition of rare earth elements Hf and Ho will improve the mechanical properties and adhesion of the oxide film, and reduce the phenomenon of oxide film peeling; oxidation process exists from the θ- Al2O3 to α- Al2O3 Phase change。

Key words: intermetallics; NiAl; high-temperature oxidation

目录

1绪论 1

1。1 高温合金概述 1

1。1。1 高温合金的强化理论 1

1。2 镍基高温合金的发展 2

1。3 高温合金的分类及用途 2

1。3。1 铁基高温合金 2

1。3。2 镍基高温合金 3

1。3。3 钴基高温合金 4

1。4 金属间化合物 4

1。5 金属间化合物高温材料 5

1。6 NiAl基高温合金 5

1．7 研究目的与意义 6

2实验部分 7

2。1 实验材料 7

2。2 实验步骤 7

2。3 实验设备与材料 7

3试验结果分析 11

3。1 氧化膜的XRD物相分析 11

3。2 氧化膜表面形貌分析 11

3。3 截面形貌分析 20

3。4 讨论 21

4 结论 22

致谢