合金元素硅和铈对镍铬合金高温氧化行为的协同作用

SYNERGETIC EFFECT OF CERIUM AND SILICON ON

研究了Ni-20Cr,Ni-15Cr-1.5Si,Ni-15Cr-1.5Si-0.5Ce合金的高温氧化行为,以探讨硅以及稀土与硅的影响。结果表明,镍铬合金中加入硅,降低氧化速率,但同时降低合金抗循环氧化能力。合金中加入稀土铈和硅,促进完整的Cr_2O_3氧化层的形成,且由于协同作用,明显地改善了氧化膜的粘附性,从而使Ni-20Cr合金中Cr含量可减少5 wt%,而合金抗氧化性能还有提高。从电子探针元素分析结果,认为稀土元素对提高氧化膜的粘附性,并不产生直接作用,而是通过促进内氧化,形成SiO_2产生钉扎作用。

The high-temperature oxidation behavior of Ni-20Cr ,Ni-15Cr-1.5Si,Ni-15Cr-1.5 Si-0. 5Ce alloys was examined. The oxidaton rate was reduced by the addition of silicon, but the scale of Ni-15Cr-1.5Si alloy was more susceptiole to spalling during cyclic oxidation. The combined addition of silicon and cerium made the alloy surface to be covered with a continuous Cr_2O_3 layer and markedly improved the scale adherence. It is concluded that the introduction of silicon and cerium into the alloy improves its oxidation resistance, even when the chromium content in the alloy was reduced from 20% to 15%. The results of EPMA showed that Ce improved the scale adherence through indirect effects by.the accelation of internal oxidation of Si resulting in the clinching of the scale into the substrate.