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采用机械合金化及热压法制备Ni-20 Cr-2.5Al、Ni-20 Cr-2.5 Al-0.8 Y2O3和Ni-20 Cr-2.5Al-3Y2O3高温合金,研究了不同含量Y2O3对Ni-20 Cr-2.5 Al合金在900℃空气中热腐蚀行为的影响。结果表明:Ni-20 Cr-2.5 Al合金在高温热腐蚀的实验初期有氧化膜剥落现象发生,而Ni-20 Cr-2.5 Al-0.8 Y2O3和Ni-20 Cr-2.5Al-3 Y2O3两种合金变化比较轻微;三种合金在氧化初期氧化增重比较明显,后期增重缓慢,涂有盐膜的Ni-20Cr-2.5Al合金的氧化增重最大,Ni-20Cr-0.8Y2O3合金次之,Ni-20Cr-2.5Al-3Y2O3合金的氧化增重最小。热腐蚀后三种合金表面的腐蚀膜分为两层,氧化膜外层主要由Al2O3组成,内层主要由靠近基体的Cr2O3组成,且Cr2O3腐蚀膜的厚度很薄。Y2O3的添加能够起到净化界面的作用,不仅提高了界面结合强度,也使得Al2O3保护膜具有更微小的晶粒,因而提高合金的抗热腐蚀性能。
Ni-20 Cr-2.5Al, Ni-20 Cr-2.5 Al-0.8 Y2O3 and Ni-20 Cr-2.5Al-3Y2O3 superalloys were prepared by mechanical alloying and hot pressing. -2.5 Al alloy in 900 ℃ air corrosion behavior. The results show that the oxide film exfoliation occurs in the initial stage of high temperature hot corrosion of Ni-20 Cr-2.5Al alloy. However, two kinds of alloys, Ni-20 Cr-2.5 Al-0.8 Y2O3 and Ni-20 Cr-2.5Al-3 Y2O3 The oxidation weight gain of the three alloys was more obvious at the initial stage of oxidation, and the weight gain was slow at the later stage. The oxidation weight gain of Ni-20Cr-2.5Al alloy coated with salt film was the largest, followed by Ni-20Cr-0.8Y2O3 alloy, and Ni -20Cr-2.5Al-3Y2O3 alloy oxidation weight gain the smallest. The corrosion film of the three alloy surfaces after hot corrosion is divided into two layers. The outer layer of the oxide film is mainly composed of Al2O3. The inner layer is mainly composed of Cr2O3 close to the matrix, and the thickness of the Cr2O3 corrosion film is very thin. The addition of Y2O3 can purify the interface, which not only improves the interfacial bonding strength, but also makes the Al2O3 protective film have more fine grains, thus improving the hot corrosion resistance of the alloy.