Effect of pre-oxidation treatments on the structural, microstructural, and chemical properties of β-(Ni,Pt)Al system

Abstract The effect of isothermal pre-oxidation treatments on the β-(Ni,Pt)Al +  IDZ  + Rene N5 system degradation is reported here. The pre-oxidation treatments were carried out from 900 °C (mostly θ-Al 2 O 3 growing conditions) to 1200 °C (mainly α-Al 2 O 3 growing conditions) for 5 h, under an Ar-stream with pO 2  = 1 × 10 −5  atm. The correlation between the structural, microstructural, and chemical properties of the β-(Ni,Pt)Al BC show that pre-oxidation parameters have an important effect on the multi-elemental counter diffusion phenomena along the BC . Heat treatments performed above 1100 °C resulted in loss of stability of the BC, partially disordering of the β phase promoting the β → β + L1 0 and β → β + L1 2 transformations. A significant BC  +  IDZ thickness increase of 55% at 1200 °C was observed with respect to the as-received specimen resulting in a severe BC degradation. Multi-elemental inward diffusion is the main mechanism responsible for BC degradation at high temperatures.