Premium
Slurry aluminizing of IN‐800HT austenitic stainless steel and pure nickel. Correlations between experimental results and modelling of diffusion
Author(s) -
Pedraza F.,
Proy M.,
Boulesteix C.,
Krukovskyi P.,
Metel M.
Publication year - 2016
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201508758
Subject(s) - slurry , materials science , metallurgy , aluminide , annealing (glass) , austenite , diffusion , nickel aluminide , nial , nickel , intermetallic , thermodynamics , composite material , microstructure , physics , alloy
Slurry aluminide coatings were elaborated on IN‐800HT and pure Ni. After spray of the slurry, the annealing treatment was performed in Ar(g) at 400 °C for 3 h, then by 650 °C for up to 5 h. This brought about major Al diffusion into the substrate following parabolic kinetics. After 5 h at 650 °C, stabilization of the B2–(Fe,Ni)Al and β‐NiAl coatings in, respectively, the IN‐800HT and pure Ni substrates was achieved at 1100 °C for 1 h. The coatings were then exposed to air, argon and steam for 2000 h at 650 °C. The Al diffusion profiles were acquired by EDS analyses and were equivalent in Ar(g) and steam whereas significant consumption of Al occurred in the external coatings exposed to air. Five hundred hours annealing steps were thus carried out in Ar(g) to gather the Al composition profiles with exposure time till 2000 h to model diffusion and to estimate lifetime. These were performed using a numerical model and the so‐called inverse problem solution, which appeared to be unsuccessful due to the insufficient quality of experimental data expressed through a quantitative criterion (“informativity”). Some recommendations are proposed to increase the accuracy of the assessment of the model parameters.