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作者研究了添加0.1％和0.8％Ce的Ni—Cr—Cu合金在空气中1200℃100小时等温氧化和500小时循环氧化。Ni—Cr—Cu合金中添加微量Ce后,显著降低了氧化速率,增加了氧化膜的剥落抗力。氧化速率降低是添加Ce后各种效应综合作用的结果。它们是:(1)由于Cr的扩散加快,富Cr保护膜更迅速形成;(2)聚集在膜/合金界面附近的含Ce氧化物与空位复合,减少了膜/合金界面的空洞;(3)固溶于氧化膜中的含Ce氧化物阻碍了Cr~(3+)沿氧化物晶界的短程扩散。提高耐剥落抗力主要原因是:(1)添加Ce使氧化膜晶粒变细,从而改善了塑性变形和适应热应力的能力;(2)0.8Ce合金中稀土氧化物“钉扎”(Keying)作用改善了膜与合金粘附性,并改变了热应力的分布状态。
The authors studied the Ni-Cr-Cu alloy with addition of 0.1% and 0.8% Ce in air at 1200 ° C for 100 hours for isothermal oxidation and 500 hours for cyclic oxidation. After adding a small amount of Ce in Ni-Cr-Cu alloy, the oxidation rate is remarkably decreased, and the exfoliation resistance of the oxide film is increased. The reduction of the oxidation rate is the result of the combined effects of various effects after the addition of Ce. They are: (1) the Cr-rich protective film formed more rapidly due to the accelerated diffusion of Cr; (2) the Ce-containing oxide and the vacancies complexed near the film / alloy interface reduced the cavities in the film / alloy interface; The Ce-containing oxide solid solution in the oxide film hinders the short-range diffusion of Cr 3+ along the oxide grain boundaries. The main reasons for improving the resistance to spalling are as follows: (1) Ce is added to make the grain of the oxide thinner so as to improve the plastic deformation and the ability to adapt to thermal stress; (2) rare earth oxide “pinning” The effect improves the adhesion of the film to the alloy and changes the distribution of thermal stresses.