Electron microscopy study of different stages of oxidation of Ti-47Al-2Nb-2Cr-0.15B and Ti-45Al-15Nb at 900 degrees C
1Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, PR China. imrwlu@gmail.com
Abstract:
The initial stage of oxidation of Ti-47Al-2Nb-2Cr-0.15B and Ti-45Al-15Nb alloys was studied. Studies reveal that the X and NbCr(2) phases will form in advance in the transition layer of the 2Nb2Cr alloy compared with the 15Nb alloy. The adherence between the nitride layer and underling layer is good. However, an obvious boundary exists between the mixed layer and the inner layer. The recrystallizing of the base alloy leads to an increase of the volume fraction of grain boundaries that can increase the oxidation rate at the initial oxidation stage. An Nb-based compound forms in the transition layer, which can prevent the formation of X phase.
