相组成对Cr-Nb合金高温氧化行为的影响  

Effect of phase constitution on oxidation behavior of Cr-Nb alloys

作　　者：郑海忠[1,2] 鲁世强[1] 王克鲁[1] 董显娟[1] 

机构地区：[1]南昌航空大学材料科学与工程学院,南昌330063 [2]南京航空航天大学材料科学与技术学院,南京210016

出　　处：《中国有色金属学报》2008年第12期2172-2177,共6页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(50474009);航空科学基金资助项目(05G56003);江西省自然科学基金资助项目(0350045);江西省材料科学与工程研究中心基金资助项目(ZX200401001)

摘　　要：采用机械活金化+热压烧结法制备5种不同相组成的Cr-Nb合金,研究相组成对Cr-Nb合金在950～1200℃空气中氧化行为的影响。结果表明,Cr相能显著增加NbCr2合金950℃的抗氧化性能;而Nb相不利于合金高温抗氧化性的提高,甚至发生灾难性氧化。SEM和XRD分析显示,单相Cr-2.5Nb合金发生了Cr的外氧化,只形成单一的Cr2O3膜;而双相Cr-18.5Nb合金和单相Laves相NbCr2合金均发生Cr的外氧化和内氧化,形成两层结构的氧化膜。但随着氧化温度增加到1200℃,由于Cr2O3的挥发,导致Cr-Nb合金高温抗氧化性变差。因此,为满足实际高温应用要求,对富软第二相Cr或Nb的NbCr2基合金实施相应的表面防护是必须的。Five types of Cr-Nb alloys with different phase constitutions were fabricated by mechanical alloying and hot pressing. The influence of phase constitution on the oxidation behavior of the hot pressed Cr-Nb alloys were investigated at 950-1 200 ℃ in air. The results show that Cr phase improves the oxidation resistance of Laves phase NbCr2 based compounds at 950 ℃. However, Nb phase deteriorated the oxidation resistance, moreover, Nb phase results in a catastrophic failure during oxidation. SEM and XRJ） analyses indicate that the Crss phase （Cr-2.5Nb） exhibits selective Cr oxidation and forms a continuous chromia scale. However, single phase alloys of Cr-33Nb and two phase alloys of Cr-18.5Nb exhibit that internal and external oxidation happen simultaneously for the active element chromium, and their oxide scales are made with a multi-layered scale consisting of an outer layer being a porous, loosely adherent Cr2O3 layer and the inner layer being of CrNbO4. With the exposure temperature increasing up to 1 200 ℃, the oxidation resistance of Cr-rich Cr-Nb alloys decreases due to the continuous vaporization of CrO3 in the oxide scale. Therefore, it is necessary to apply surface protective coatings on Cr（or Nb）-NbCr2 alloys to promote their application in the high temperature environment.

关 键 词：Cr-Nb合金 LAVES相 软第二相 相组成 氧化行为 

分 类 号：TG132.3[一般工业技术—材料科学与工程] TG174.3[金属学及工艺—合金]