Preparation and enhanced oxidation performance of a Hf-doped single-phase Pt-modified aluminide coating

A Hf-doped beta-(Ni,Pt)Al coating was prepared by co-deposition of a Pt-Hf composite plating and successive aluminisation. Then, a distinct Hf-rich belt was formed internally between the outer additive (Ni,Pt)Al coating and interdiffusion zone. An isothermal oxidation test at 1100 degrees C revealed a relatively lower oxidation rate constant and decreased oxide scale rumpling tendency for the Hf-doped coating during which the Hf-rich belt partly acted as an effective diffusion barrier. The unique addition of Hf into a beta-(NLPt)Al coating can delay the transitional oxidation period from transient alumina to stable one and postpone the degradation from beta to gamma'. (C) 2016 Elsevier Ltd. All rights reserved.