Si对Ni-xAl合金900℃氧化行为的影响

SILICON EFFECTS ON THE OXIDATION OF Ni-xAl ALLOYS AT 900 ℃

研究了三元Ni-6Si-xAl(x=6,10,15,原子分数, %)合金在900℃, 0.1 MPa纯氧气中的氧化行为.二元Ni—Al合金形成了外NiO膜,并伴随有Al的内氧化.而所有三元合金锈层底部均形成了连续完整的外Al2O3膜,防止了Al 的内氧化,从而显著降低了三元合金的腐蚀速率.因此,与二元Ni—Al合金相比, Si的存在能非常有效的减少形成Al2O3膜所需的临界Al含量.在对Wagner关于二元合金中最活泼组元由内氧化向外氧化转变判据理论进行扩展的基础上,阐述了第三组元Si的作用.

The oxidation of three ternary Ni-6Si-xAl （x=6, 10, 15, atomic fraction,%） alloys has been studied at 900 ℃ in 0.1 MPa O2. The three binary Ni-Al alloys formed external NiO scales associated with an internal oxidation of aluminum. On the contrary, all the ternary alloys formed a continuous external scale of alumina directly in contact with the metal substrate, which inhibited the internal oxidation of aluminum and reduced considerably the corrosion rate. Thus, the presence of silicon is very effective to reduce the critical aluminum content needed for the formation of exclusive alumina scales with respect to binary Ni-Al alloys. The third-element effect due to silicon has been interpreted on the basis of an extension of Wagner＇s criterion for the transition from the internal to the external oxidation of the most reactive component in binary alloys.