预氧化温度对Ni-20Cr-5Al-0.2Y2O3合金抗高温循环氧化性能的影响

摘要

通过粉末冶金方法制备了Ni-20Cr-5Al和Ni-20Cr-5Al-0.2Y2O3(质量分数/%,下同)合金,将Ni-20Cr-5Al-0.2Y2O3合金在不同温度(500~1 100 ℃)进行预氧化处理,然后将未预氧化及预氧化合金在1 150 ℃下循环氧化15 h,研究了Y2O3的添加和不同预氧化温度对合金抗高温循环氧化性能的影响.结果表明:添加0.2%Y2O3后提高了Ni-20Cr-5Al合金的抗高温循环氧化性能;预氧化可以有效提高Ni-20Cr-5Al-0.2Y2O3合金的抗高温循环氧化性能,其中预氧化温度为700 ℃的合金有最优的抗高温循环氧化性能,其原因是经过预氧化处理的合金表面形成了致密的保护性氧化膜,阻止了氧化的进一步进行.%Ni-20Cr-5Al and Ni-20Cr-5Al-0.2Y2O3 (mass fraction/%) alloys were prepared by powder metallurgic technology.The Ni-20Cr-5Al-0.2Y2O3 alloy was first pre-oxidized at different temperatures from 500 ℃ to 1 100 ℃, and then the un-oxidized and pre-oxidized alloys were cyclic oxidized at 1 150 ℃ for 15 h.The effects of Y2O3 and pre-oxidation temperature on the high-temperature cyclic oxidation resistance of the alloys were studied.The results show that the high-temperature cyclic oxidation resistance of Ni-20Cr-5Al alloy was improved with the addition of 0.2wt% Y2O3.The pre-oxidation can improve the high-temperature oxidation resistance of Ni-20Cr-5Al-0.2Y2O3 alloy effectively.Furthermore, when the pre-oxidation temperature was 700 ℃, the alloy achieved the best high-temperature cyclic oxidation resistance.The reason is that a dense protective oxide scale was formed on the surface of the alloy after pre-oxidation, which prevented the alloy from the further oxidation.