Effects of Prehafnizing on Morphological Development of a Chemical Vapor Deposition Aluminide Coating Formed on Single-Crystal Ni-Based Superalloy

L. M. He, J. D. Meyer, W. Y. Lee

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

We examined a sequential Hf doping procedure, which consisted of (1) "prehafnizing" the surface of a single-crystal Ni-based superalloy (RENÉ N5) with HfCl4 and H2, and (2) aluminizing with AlCl3 and H2, as a means of incorporating Hf as a dopant in the aluminide coating matrix. The prehafnized layer on RENÉ N5 substrate significantly altered the growth behavior and therefore the morphology of the resulting aluminide coating. With the prehafnizing step, the coating layer became much thinner with a significant amount of Hf incorporated as Hf-rich phases (Hf2Ni7, Hf3Ni7, and/or Hf8Ni21). However, the Hf-rich phases segregated to the coating surface and retarded the inward Al diffusion required to form the β-NiAl coating matrix. The sequential Hf doping procedure provided a mechanism to incorporate a significant amount of Hf in the coating, but did not produce a uniform distribution of Hf as a dopant. The results were compared to those observed for a continuous doping procedure that was previously studied, and were discussed in the context of understanding the limitations of these procedures.

Original languageEnglish
Pages (from-to)891-897
Number of pages7
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume35 A
Issue number3
DOIs
StatePublished - Mar 2004

Fingerprint

Dive into the research topics of 'Effects of Prehafnizing on Morphological Development of a Chemical Vapor Deposition Aluminide Coating Formed on Single-Crystal Ni-Based Superalloy'. Together they form a unique fingerprint.

Cite this