NiAl共晶合金的高温氧化行为的研究+文献综述
关键词：NiAl共晶合金；高温氧化；氧化动力学;毕业论文
High Temperature Oxidation Behavior of a NiAl Eutectic Alloy
Abstract：Long-range ordered intermetallic compound NiAl has a high melting point，low density，good oxidation resistance，high thermal conductivity，high Young 's modulus range of characteristics．But its application is limited because of its poor ductility at room temperature and low high temperature strength at high temperature．Therefore，NiAl-Cr (Mo) alloys have been prepared by directionally solidified method．A new type of NiAl -based eutectic alloy is obtained through an appropriate amount of Hf，Ho element has been added to NiAl-Cr (Mo) substrate，forming Heusler phase precipitation strengthening．NiAl-Cr (Mo)-Hf-Ho alloy at 900℃ for the isothermal oxidation behavior was studied by using a static weight increase，the oxidation kinetics were measured．The results indicate that oxidation kinetics approximately obey the parabolic law．The oxidation scales on the surface were determined by means of XRD，SEM and EDS．The results show that oxidation scale was consisted of Cr2O3，A12O3，HfO2 on the surface of the alloy．Surface oxidation scale adhesion and anti-stripping capability is improved by the addition of small amounts of active elements Hf，Ho．So that the alloy has good oxidation resistance．
KeyWords：NiAl eutectic alloy；High-temperature oxidation；Oxidation kinetics
目 录
1绪论 1
1.1 引言 1
1.2 NiAl的物理性质 1
1.3 NiAl基合金氧化机理讨论 3
1.4 NiAl基合金氧化动力学分析 4
1.4.1合金的保护性氧化膜 5
1.4.2金属／氧化膜界面 5
1.4.3相(晶)界氧化与内氧化 6
1.5 NiAl基合金氧化膜的组成 7
1.6多元合金的氧化 8
1.6.1 A12O3氧化膜的生长机制 8
1.6.2 Cr2O3氧化膜的性质和生长机制 9
1.7研究本课题的目的和意义 10
2本课题的研究内容、实验方法 11
2.1研究内容 11
2.2实验方法 11
2.3 实验仪器及设备 11
2.4实验步骤 15
3实验结果与分析 16
3.1 实验合金的显微组织 16
3.2 氧化动力学曲线 17
3.3氧化膜的组成 19
3.4表面氧化膜的形貌 20
3.6氧化膜断面形貌与组成 23
3.7讨论 24
4 结论 25
致谢 26
参考文献 27
1绪论
1.1 引言
随着航空航天工业的迅速发展，为了满足燃气涡轮发动机的高推重比、高增压比和高涡轮前温度的三高要求，对高温结构材料的要求也越来越高。高温合金尽管有较好的稳定性，但使用温度己达到其绝对熔点温度的80%[1]，接近它们的极限。目前材料学界面临的一个重大挑战是研制新一代的高温合金以替代飞行器推进系统中燃气涡轮发动机热端部件的镍基高温合金。众所周知，替代镍基高温合金的新一代材料必须具备高强度、高熔点、低密度、优异的高温抗氧化性、组织稳定和成本低廉等特点。