(沈阳师范大学化学与生命科学学院，沈阳110034)
摘 要: 通过热压采用机械合金化(MA)法合成的合金粉末制备纳米晶块体Fe-60Ni-15Cr(MA)合金，并与粉末冶金(PM)法制备的常规尺寸Fe-60Ni-15Cr(PM)合金对比，研究两种合金在700~900℃、0.1MPa纯氧中的氧化行为以及晶粒细化对其氧化行为的影响。结果表明：Fe-60Ni-15Cr(PM)和Fe-60Ni-15Cr(MA)合金的氧化动力学曲线均偏离抛物线规律。在相同温度下，纳米尺寸Fe-60Ni-15Cr(MA)合金的氧化速率明显低于常规尺寸Fe-60Ni-15Cr(PM)合金的。Fe-60Ni-15Cr(PM)合金表面没有形成保护性的Cr2O3膜，而是形成了由Fe的氧化物组成的外氧化膜和由Fe、Ni和Cr氧化物组成的内层，并有合金和氧化物相组成的混合内氧化形成。相反Fe-60Ni-15Cr(MA)合金表面则只形成了保护性的Cr2O3外氧化物膜。因此，晶粒细化有利于降低合金表面形成连续Cr2O3外氧化膜所需Cr的临界含量，促使合金能在较低的Cr含量下形成连续有保护性的Cr2O3外氧化膜。
关键字: Fe-Ni-Cr合金；晶粒细化；纳米晶；高温氧化
（College of Chemistry and Life Science, Shenyang Normal University, Shenyang 110034, China）
Abstract:Nanocrystalline bulk Fe-60Ni-15Cr alloy was prepared by hot pressing alloyed powders synthesized by mechanical alloying (MA) method. High temperature oxidation behavior of the alloy was investigated at 700-900℃ in 0.1MPa pure oxygen，compared with the corresponding coarse grained Fe-60Ni-15Cr alloy prepared by powders metallurgy (PM) technique. The results show that the oxidation kinetics of Fe-60Ni-15Cr(PM) and Fe-60Ni-15Cr(MA) alloys deviate parabolic rate law. At the same temperatures, the oxidation rate of nanocrystalline Fe-60Ni-15Cr(MA) alloy is lower than that of coarse grained Fe-60Ni-15Cr(PM) alloy. Coarse grained Fe-60Ni-15Cr(PM) alloy is unable to form the continuous and protective scales of Cr2O3. In fact, the alloy forms the external Fe oxide scales followed by a layer composed by Fe, Ni and Cr oxides, and there is an internal oxidation in the alloy. On the contrary, nanocrystalline Fe-60Ni-15Cr(MA) alloy is able to form the continuous and protective scales of Cr2O3. It is oblivious that the grain refinement is able to decrease the critical Cr content which is required to form the continuous and protective scales of Cr2O3 and is helpful to form the continuous scales of Cr2O3 under Fe-Ni-Cr alloy surface.
Key words: Fe-Ni-Cr alloys; grain refinement; nanocrystalline; high temperature oxidation
