View Generic Document: Diffusion in Nickel-Base Superalloys and Bond Coats
Citation:
Mesick, Nathan (2005). Diffusion in Nickel-Base Superalloys and Bond Coats. National Institute of Standards and Technology, Technology Administration, U.S. Department of Commerce..
Nickel-base superalloys are known for their high temperature strengths and their corrosion resistant properties. To increase the service temperatures of the Ni-base superalloys,
thermal barrier coatings (TBC) are used in conjunction with a bond coat. The role of the bond coat is to prevent diffusion between the superalloy and the TBC, especially the depletion of Al from
the superalloy. Diffusion studies between various bond coat materials and Ni-base superalloys were conducted for two purposes: (1) to better understand the interaction between the bond coats and
the superalloys and (2) to provide data to evaluate the current diffusion mobility database. Superalloys considered in this study were Inconel X-750, Inconel 625, Inconel 718, and CMSX-4. Bond
coatings considered were RuAl, PtAl, and Ni. Diffusion couples were heat treated at 1150 C and 850 C for various times. For Ni/superalloy couples, diffusion simulations using multicomponent
thermodynamics and diffusion mobility databases were performed. Evaluation of the bond coats and the diffusion mobility database required measurement of phase fraction and composition profiles.
Optical metallography and image analysis software were used to measure the phasefraction profiles. Electron diffraction spectroscopy (EDS) was used to measure the composition profiles. This data
was used to determine how well the bond coatings limited diffusion of Al out of the superalloy and into the bond coat. Comparison of the measured and calculated composition profiles and phase
fraction profiles indicated whether specific mobility parameters or thermodynamic descriptions should be re-evaluated.
Publisher
National Institute of Standards and Technology, Technology Administration, U.S. Department of Commerce.
Guest - January 07, 2009
View Generic Document: Diffusion in Nickel-Base Superalloys and Bond Coats 