Stresses induced in alloys by selective oxidation

Mechanisms Associated with Rumpling of Pt-Modified Beta-NiAl Coatings

“…Many reports have shown that large stresses can form due to the TGO growth and void formation can occur from oxidation and interdiffusion between the TGO, coating, and substrate [14,15]. In this section these effects and subsequent consequences will be discussed so that a better understanding of TBC failure can be obtained.…”

“…Suo et al [14] numerically showed how a binary alloy can generate stress due to preferential oxidation of one of the constituents. The authors explains that in an alloy containing A and B atoms, with A forming an adherent oxide a flux divergence occurs (known as Kirkendall effect).…”

Rumpling phenomenon in platinum modified Ni-Al alloys

“…A numerical study of the stresses that can be induced in alloys where one element is preferentially oxidized is provided in a 2003 paper by Suo et al [28]. While Suo's paper provides numerical examples for the Pt-modified NiAl system, the general ideas can be applied to a wide range of alloys.…”

Focused ion beam assisted analysis of the oxidation of a NiAl coating on pure Ni

“…The oxidation of NiAl coatings and Pt modified NiAl coatings is frequently accompanied by the formation of subscale voids [1,2]. Furthermore, beneath spalled regions faceted intrusions into the coatings can also be observed [3,4].…”

“…Furthermore, beneath spalled regions faceted intrusions into the coatings can also be observed [3,4]. In addition, Al depletion effects due to oxidation and interdiffusion effects between coatings and substrate induce strains of sufficient magnitude for void formation [2]. In order to investigate these effects more readily, it is useful to work with a model system such that irregularities induced by second phases e.g.…”