镧和铈对Fe25Cr5Al合金高温氧化行为的影响

Effect of La and Ce on High Temperature Oxidation Behavior of Fe25Cr5Al Alloys

含稀土元素La、Ce的Fe25Cr5Al-RE合金和不含稀土的Fe25Cr5Al合金在1100℃的空气中进行了恒温氧化实验。采用扫描电子显微镜(SEM)观察氧化膜形貌,使用X射线衍射仪(XRD)结合能谱仪(EDS)分析氧化膜成分。结果表明,氧化1、20和300 h后,Fe25Cr5Al合金增重分别为0.08、0.84和4.41 mg·cm^(−2),Fe25Cr5Al-RE合金增重分别为0.03、0.35和0.92 mg·cm^(−2)。氧化后所有合金的氧化膜成分均为α-Al_(2)O_(3)。La、Ce能够促进合金形成致密、连续的氧化膜,显著提高了Fe25Cr5Al合金的抗高温氧化性能。此外,Fe25Cr5Al-RE合金氧化膜/基体界面存在稀土氧化物钉,使得氧化膜与基体的结合更加紧密,增强了氧化膜/基体粘附性。Fe25Cr5Al-RE合金氧化后,氧化膜内存在稀土氧化物,有效地防止了合金发生进一步氧化。

Fe25Cr5Al alloys with and without rare earth(RE)elements La and Ce,namely Fe25Cr5Al-RE and Fe25Cr5Al alloys,were prepared and isothermal oxidation tests were conducted at 1100℃.The morphology of oxide scale was observed by scanning electron microscope(SEM),and the oxidation product was identified by energy disperse spectroscopy(EDS)coupled with X-ray diffraction(XRD).Results show that after oxidation for 1,20,and 300 h,the mass gain of Fe25Cr5Al alloys is 0.08,0.84,and 4.41 mg·cm^(−2),but that of Fe25Cr5Al-RE alloys is 0.03,0.35,and 0.92 mg·cm^(−2),respectively.The oxide scale of the two alloys consists ofα-Al_(2)O_(3).La and Ce promote the formation of compact and continuous oxide scale,which significantly improves the high temperature oxidation resistance of Fe25Cr5Al alloys.Moreover,RE oxide pegs can be observed at substrate/scale interface of Fe25Cr5Al-RE alloys,which makes the bond between substrate and scale tighter,thus enhancing the adhesion of the interface.There are RE oxides in oxide scale of Fe25Cr5Al-RE alloys,which effectively inhibits further oxidation of the alloys.