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对单一添加及同时添加La和Hf的CoNiCrAl合金进行真空高温氧化处理,研究单一添加与同时添加La和Hf对合金表面氧化物生长机制和黏结性能的影响.结果表明:表面抛光的合金在1100℃氧化时,同时添加La和Hf使CoNiCrAl合金在其表面形成了连续均匀的Al_2O_3,并且具有较好的黏结性能.通过~(18)O追踪原子氧化发现CoNiCrAlLa,CoNiCrAlHf和CoNiCrAlLaHf合金的Al_2O_3生长均为O~(2-)内扩散为主的生长机制,同时伴随少量的金属离子外扩散.单一添加La和Hf,形成的Al_2O_3表面富集Cr,Co和Ni等,且随Al_2O_3深度增加而逐渐降低,这些元素促使Al_2O_3表面形成Ni(Co)Al_2O_4,从而降低Al_2O_3的黏结性能.同时添加La和Hf,没有改变O~(-2)内扩散为主的生长机制,但Hf能够阻碍La在氧化物/合金界面的富集,减少Ni(Co)Al_2O_4形成,同时合金表面局部内氧化的钉扎效应提高了Al_2O_3的黏结性能.
The effects of single addition and simultaneous addition of La and Hf on the growth mechanism and the bonding properties of the surface oxides of the alloys were investigated by vacuum high temperature oxidation of CoNiCrAl alloy with addition of La and Hf.It was found that the surface alloying at 1100 ℃ Oxidation, the addition of La and Hf at the same time make CoNiCrAl alloy form continuous and uniform Al_2O_3 on its surface and have good bonding performance.The growth of Al_2O_3 of CoNiCrAlLa, CoNiCrAlHf and CoNiCrAlLaHf alloy was observed by ~ (18) O tracking atomic oxidation O ~ (2-) diffusion with the addition of a small amount of metal ions.The single addition of La and Hf, the formation of Al 2 O 3 surface enrichment of Cr, Co and Ni, etc., and with increasing depth of Al 2 O 3 gradually decreased , These elements promoted the formation of Ni (Co) Al_2O_4 on the surface of Al_2O_3, which reduced the bonding property of Al_2O_3, and the addition of La and Hf did not change the growth mechanism of O_ (-2) / Alloy interface to reduce the formation of Ni (Co) Al_2O_4, and the pinning effect of local internal oxidation on the surface of the alloy improves the bonding property of Al_2O_3.