Effect of Cerium on Microstructures and High Temperature Oxidation Resistance of An Nb-Si System In-Situ Composite
来源期刊：JOURNAL OF RARE EARTHS2007年第4期
论文作者：Han Yafang Li Shusuo Liu Aiqin Sun Lu
Key words：oxidation resistance; in-situ composite; Nb-Si alloy; rare earths;
Abstract: Nb-16Si-24Ti-6Cr-6Al-2Hf-xCe (x=0, 0.05, 0.1, 0.25, 0.5, 1 (%, atom fraction)) in situ composites were prepared by arc melting. The microstructure and the effect of rare earth element cerium on 1250 ℃ oxidation resistance of the composites were investigated with scanning electron microscopy (SEM) and X-ray energy disperse spectrum (EDS), as well as X-ray diffraction (XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was improved by adding a proper amount of cerium (Ce). The effect of Ce was considered as the concurrent of the following three factors: first, the oxide of Ce formed in the interface reduced the internal oxidation rate; second, the lath shaped oxide containing Ce increased the cracking resistance and reduced the expansion of the oxide scale; and third, the decrease of the silicide volume fraction on account of Ce addition reduces the power of the sample resisting oxy gen penetration.
Han Yafang1，Li Shusuo1，Liu Aiqin1，Sun Lu1
(1.School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China)
Abstract:Nb-16Si-24Ti-6Cr-6Al-2Hf-xCe (x=0, 0.05, 0.1, 0.25, 0.5, 1 (%, atom fraction)) in situ composites were prepared by arc melting. The microstructure and the effect of rare earth element cerium on 1250 ℃ oxidation resistance of the composites were investigated with scanning electron microscopy (SEM) and X-ray energy disperse spectrum (EDS), as well as X-ray diffraction (XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was improved by adding a proper amount of cerium (Ce). The effect of Ce was considered as the concurrent of the following three factors: first, the oxide of Ce formed in the interface reduced the internal oxidation rate; second, the lath shaped oxide containing Ce increased the cracking resistance and reduced the expansion of the oxide scale; and third, the decrease of the silicide volume fraction on account of Ce addition reduces the power of the sample resisting oxy gen penetration.
Key words:oxidation resistance; in-situ composite; Nb-Si alloy; rare earths;
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