通过光学显微镜、X射线衍射、扫描电镜和热重分析等研究了添加铈对Cu-3Si-0Ce合金在800℃、0.1 MPa纯氧气中高温氧化行为的影响.结果表明,添加0.5％和1.0％(质量分数)的铈明显提高了合金的氧化抗力.随着铈含量的增加,Cu-3Si-0Ce合金及其氧化膜的晶粒尺寸明显降低,这促进了合金元素和氧的“短路扩散”,有利于SiO2和CeO2在氧化膜内层的富集,降低了合金的氧化速率.较薄的氧化膜、合金元素快速的扩散速率和铈对氧化膜孔洞的补偿、晶粒细化对氧化膜力学性能的改善以及钉扎效应是含铈合金氧化膜具有较好粘附性的主要原因.Cu-3.0Si-1.0Ce中过量的铈参与氧化反应,使氧化膜中CeO2的质量分数提高,而过量CeO2的生成对氧化膜生长抑制作用的提高并不明显,故其表现出更大的氧化增重.
The effect of Ce on high temperature oxidation behavior of Cu-3Si alloy at 800 ℃ in 0.1 MPa flowing pure O2 has been investigated by means of optical microscope,thermogravimetric analysis,X-ray diffraction and scan electron microscope.Results show that the addition of 0.5％ and 1.0％ Ce (mass fraction) improved the oxidation resistance of the alloy significantly.As the content of Ce increases,the grain size of Cu-3Si-Ce alloy and its oxides decreases obviously,which promotes the short-path diffusion of the alloying elements/oxygen and the enrichment of CeO2 and SiO2 at the inner side of the oxide scales,and thus the oxidation rate of the Ce-containing alloy is reduced.The relatively thinner oxide scales,the rapid diffusion rate of alloying elements and the compensation of Ce on holes in oxide scales,the improvement of grain-size reduction on the mechanic properties of oxide scales and the pinning effect are the main reasons for the good adhesion of oxide scales on Ce-containing alloys.In Cu-3.0Si-1.0Ce alloy,excessive Ce takes part in the oxidation reaction,which makes the mass fraction of CeO2 increase,and the inhibitory-effect improvement of the superfluous CeO2 on the growth of oxide scales is not obvious,so the alloy exhibits larger mass gain.
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