NiAl-30．9Cr-3Mo-0．1Dy合金的微观结构与高温氧化行为

研究了NiAl 30 9Cr 3Mo 0 1Dy合金的微观组织以及在 1300~1500K空气中的恒温氧化行为。实验结果表明,加入微量Dy使合金组织细化,表现为单位体积中共晶团数目增多,Cr(Mo)层片间距减小和Cr(Mo)层片细化。增韧相(Cr(Mo) )与基体相NiAl的互相析出,有利于层状的氧化膜形成,进而提高合金的抗高温氧化性能。合金在 1500K氧化动力学曲线基本上遵循抛物线关系;而氧化温度在 1350~1450K之间,氧化动力学曲线很好地符合立方抛物线关系;当温度为 1300K时,氧化动力学曲线则符合五次方关系。立方抛物线氧化速率常数低于未合金化NiAl的抛物线氧化速率常数,并随着温度降低和氧化时间的延长而逐渐变小,合金的氧化表观激活能为 205kJ/mol。

The Microstructure and Oxidation Behavior for NiAl-30.9Cr-3Mo-0.1Dy Alloy at High Temperature

The microstructure and isothermal oxidation behavior of NiAl-30.9Cr-3Mo-0.1Dy alloy at temperature range of 1300~1500K in air atmosphere was investigated.The results revealed that the microstructure of tested alloy was fined by doping Dy, which caused the more quantity of grain cells and the finer spacing between Cr(Mo) fibers as well as smaller Cr(Mo) rods. The strengthening phase Cr(Mo) and matrix NiAl phase reciprocally precipitated in each other, which was beneficial to form the duplex-layered oxidation scale and improve the anti-oxidation properties at high temperature. The Kinetics of isothermal oxidation of NiAl-30.9Cr-3Mo-0.1Dy alloy at 1500K obeyed parabolic rule, and followed quintic equation at 1300K, and the others obeyed the cubic relation. The oxidation rate constants decreased with the decreasing temperature and elongation of exposure time. The activation energy of isothermal oxidation was calculated about 205kJ/mol.