Oxidation behavior of ternary Fe-15Cu-5Al and Fe-85Cu-5Al alloys in pure oxygen at 900 ℃
(1.江西省南昌市江西科技师范学院江西省表面工程重点实验室
2.辽宁省沈阳市科学院金属研究所金属腐蚀与防护国家重点实验室
3.湖南省湘潭市湘潭大学低维材料及应用技术教育部重点实验室
4.State Key Laboratory for Corrosion and Protection, Institute of Metal Research,Chinese Academy of Sciences, Shenyang 110016, China
5.Jiangxi Key Laboratory of Surface Engineering,Jiangxi Science and Technology Normal University, Nanchang 330013, China)
2.辽宁省沈阳市科学院金属研究所金属腐蚀与防护国家重点实验室
3.湖南省湘潭市湘潭大学低维材料及应用技术教育部重点实验室
4.State Key Laboratory for Corrosion and Protection, Institute of Metal Research,Chinese Academy of Sciences, Shenyang 110016, China
5.Jiangxi Key Laboratory of Surface Engineering,Jiangxi Science and Technology Normal University, Nanchang 330013, China)
Abstract: The oxidation of two two-phase ternary Fe-Cu-Al alloys containing about 5%(mole fraction) aluminium, one Fe-rich and one Cu-rich, has been studied at 900 ℃ in 1×105 Pa pure oxygen. The Fe-rich Fe-15Cu-5Al alloy presents two quasi-parabolic stages, with a large decrease of the parabolic rate constant after about 50 min. The presence of 5% Al greatly reduces the oxidation rate of this alloy with respect to a binary Fe-Cu alloy of similar composition by forming an external protective Al2O3 layer, which is present near the scale/alloy interface. Due to the high stress-growth effect, this thin Al2O3 layer cannot completely prevent further oxidation of the alloy underneath. On the contrary, the Cu-rich Fe-85Cu-5Al alloy presents a single parabolic stage and forms a thick and porous external scale, coupled to the internal oxidation of Fe and Al. As a result, the oxidation of Cu-rich alloy at 900 ℃ is much faster than that of the Fe-rich alloy.
Key words: Fe-15Cu-5Al alloy; Fe-85Cu-5Al alloy; ternary alloy; oxidation behavior