The role of microstructure on oxidation of Ni-Cr-Al base alloys at 1023 and 1123 K in air

The Effect of Volatilisation of Refractory Metal Oxides on the Cyclic Oxidation of Ni-base Superalloys

“…Statistical analysis of the mass loss data (after 100 cycles) through the experimental design highlighted both Mo and Co to be detrimental to cyclic oxidation performance, with Mo explaining 79% of the variation in mass loss, see Figure 2. This behaviour is consistent with the other work in the literature that has also shown Mo to have a negative impact on cyclic oxidation performance [15,16]. These observations were refined by the XRD analyses, see…”

“…There also is clear evidence that Re, Ru and Mo has been lost through volatilisation/sublimation during cyclic oxidation of Ni-base superalloys at typical operating temperatures. This work therefore supports the other indirect observations of this phenomena and the resultant impact [5][6][7][8][9][10][11][12][13][14][15][16][17], and serves to highlight some of the additional potential risks with the increased levels of these elements in modern superalloy compositions. This observation could be further strengthened by performing experiments where a mass spectrometer is coupled to a TGA to directly measure the evolution of volatile species, such as the approach detailed in [19].…”

“…Whilst the boiling point of MoO 3 is relatively high (1155°C) it has been shown to sublime at temperatures as low as 450°C [14]. Mo has been reported to have a negative impact on the cyclic oxidation resistance of Ni-base superalloys by a number of authors [15,16], and MoO 3 itself has been observed as a condensed phase after oxidation [17]. This paper further investigates refractory oxide volatilisation using a range of approaches to further elucidate this phenomenon.…”

Corrosion behaviour of the new gas turbine alloy 2100 GT in hot gases and combustion products

“…Gonzalez Carrasco et al observed, that the addition of refractory elements on the oxidation behaviour of Ni-Cr-Al-alloys leads to a significant higher mass gain resulting in a poorer oxidation resistance [7]. The diffusion coefficient of chromium and aluminium is impaired by the refractory elements which lowers the migration of these elements to the surface and inhibits the formation of a protecting oxide scale.…”

Evaluation of Ruthenium-Bearing Single Crystal Superalloys: A Design of Experiments

“…Any subsequent loss of the initial oxide layer would reveal a substrate more depleted in aluminium and therefore less able to re-form a protective oxide scale. Although the work conducted to date does not explain the results from the DoE, the negative impact of Mo on the cyclic oxidation performance of Ni-base superalloys is well documented [15,16]. Mo is known to form MoO 3 at elevated temperatures [17], indeed, this has been observed as a condensed phase following the high temperature oxidation of Ni-base superalloys [18].…”