Accession Number : AD0760365

Title :   Kinetics of Phase Layer Growth During Aluminide Coating of Nickel.

Descriptive Note : Technical rept.,

Corporate Author : CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF METALLURGY AND MATERIALS SCIENCE

Personal Author(s) : Hickl,Anthony J. ; Heckel,Richard W.

Report Date : APR 1973

Pagination or Media Count : 31

Abstract : The diffusion coating of nickel with aluminum was studied by a two-step process involving initially an influx of aluminum at the surface (aluminization) and later a partial homogenization of the aluminum-rich region under conditions of zero surface flux. The two-step process was studied in the temperature range from 870 to 1000C. The aluminization step was characterized mainly as the rapid, parabolic growth of the Ni2Al3 phase (gamma) at the surface. The homogenization step was characterized mainly as the relatively slow thickening of the NiAl phase (delta), primarily by the solution of the gamma phase. A mathematical model was developed, using numerical methods and computer techniques, which yielded growth rate predictions for the various phase layers in agreement with experimental data. The model was used to define the critical parameters controlling growth kinetics for the two-step process. (Author)

Descriptors :   (*ALUMINUM COATINGS, *NICKEL ALLOYS), DIFFUSION COATING, PHASE STUDIES, MATHEMATICAL MODELS

Subject Categories : Coatings, Colorants and Finishes

Distribution Statement : APPROVED FOR PUBLIC RELEASE