Effects of a tungsten addition on the morphological evolution, spatial correlations and temporal evolution of a model Ni-Al-Cr superalloy.
The effect of adding 2 at.% W to a model Ni-Al-Cr superalloy on the morphological evolution, spatial correlations and temporal evolution of g'(L12)-precipitates at 1073 K is studied with scanning electron microscopy and atomic force microscopy. Adding W yields a larger microhardness, earlier onset of spheroidal-to-cuboidal precipitate morphological transition, larger volume fraction (from {approx}20 to 30%), reduction in coarsening kinetics by one third and a larger number density (Nv) of smaller mean radii (<R>) precipitates. The kinetics of <R> and interfacial area per unit volume obey t1/3 and t-1/3 relationships, respectively, which is consistent with coarsening driven by interfacial energy reduction. The Nv power law dependencies deviate, however, from model predictions indicating that a stationary-state is not achieved. Quantitative analyses with precipitate size distributions, pair correlation functions, and edge-to-edge interprecipitate distance distributions gives insight into 2D microstructural evolution, including the elastically driven transition from a uniform g'-distribution to one-dimensional <001>-strings to eventually clustered packs of g'-precipitates in the less densely packed Ni-Al-Cr alloy.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); Northwestern University Grants
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 925381
- Report Number(s):
- ANL/MSD/JA-60656; ACMAFD; TRN: US200807%%331
- Journal Information:
- Acta Materialia, Vol. 56, Issue 3 ; Feb. 2008; ISSN 1359-6454
- Country of Publication:
- United States
- Language:
- ENGLISH
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