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研究了两种镍基高温合金上的渗Al层的退化过程。两种合金用两种方法施加的涂层组织相似:外层以NiAl+Ni_2Al_3为母体,上面弥散着Ti(C,N)和Al_3Ti;内层由NiAl,Ni_3Al,Ti(C,N),M_(23)C_6和M_6C等相组成。渗Al层高温氧化时的退化与外层相变紧密相关,其过程如下: Ni_2Al_3+NiAl(富Al)→NiAl(富Ni)→NiAl+Ni_3Al→Ni_3Al→Ni_3Al+γNi_2Al_3和NiAl(富Al)相极不稳定,而NiAl(富Ni)相十分稳定。Ni_3Al沿NiAl晶界生核标志着渗层退化的开始,渗层NiAl完全变成Ni_3Al+γ是退化的终了。
Degradation of Al layers on two Ni-based superalloys was investigated. The microstructures of the two alloys were similar by two methods: the outer layer was composed of NiAl + Ni_2Al_3 matrix with Ti (C, N) and Al_3Ti dispersed therein; the inner layer was composed of NiAl, Ni_3Al, Ti (C, N) (23) C_6 and M_6C phase composition. The degradation of Al infiltration layer during high temperature oxidation is closely related to the outer phase transformation. The process is as follows: Ni 2 Al 3 + NiAl (Al rich) → NiAl (Ni rich) → NiAl + Ni_3Al → Ni_3Al → Ni_3Al + γNi_2Al_3 and NiAl (Al rich) Very unstable, and NiAl (Ni-rich) phase is very stable. The nucleation of Ni_3Al along the NiAl grain boundaries marked the beginning of the degenerated layer. The delamination of the NiAl layer completely changed to Ni_3Al + γ.