期刊
ACTA MATERIALIA
卷 171, 期 -, 页码 306-333出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2019.03.016
关键词
Nickel-based superalloys; Atom-probe tomography; Temporal evolution; Monovacancy-mediated lattice kinetic; Monte Carlo; Lifshit-Slyozov (LS) model
资金
- National Science Foundation, Division of Materials Research [DMR-1610367 001]
- NSF MRI [DMR-0420532]
- ONR-DURIP [N00014-0400798, N00014-0610539, N00014-0910781, N00014-1712870]
- MRSEC program at the Materials Research Center [NSF DMR-1720139]
- SHyNE Resource [NSF ECCS-1542205]
- Initiative for Sustainability and Energy (ISEN) at Northwestern University
- E.I. DuPont de Nemours Co.
- Dow Chemical Company
- Northwestern University
- U.S. DOE [DE-AC02-06CH11357]
- W. P. Murphy Fellowship
- NSF grant
- China Scholarship Council
- Scientific HR Development Program of the Middle East Technical University
The temporal evolution of ordered gamma'(L1(2))-precipitates precipitating in a disordered gamma(f.c.c.) matrix is studied in extensive detail for a Ni-12.5 Al at.% alloy aged at 823 K (550 degrees C), for times ranging from 0.08 to 4096 h. Three-dimensional atom-probe tomography (3-D APT) results are compared to monovacancy-mediated lattice-kinetic Monte Carlo (LKMC1) simulations on a rigid lattice, which include monovacancy-solute binding energies through 4th nearest-neighbor distances, for the same mean composition and aging temperature. The temporal evolution of the measured values of the mean radius, (R(t)>, number density, aluminum supersaturations, and volume fraction of the gamma'(L1(2))-precipitates are compared to the predictions of a modified version of the Lifshitz-Slyozov diffusion-limited coarsening model due to Calderon, Voorhees et al. The resulting experimental rate constants are used to calculate the Gibbs interfacial free-energy between the gamma(f.c.c.)- and gamma'(L1(2))-phases, which enter the model, using data from two thermodynamic databases, and its value is compared to all exiting values. The diffusion coefficient for coarsening is calculated utilizing the same rate-constants and compared to all archival diffusivities, not determined from coarsening experiments, and it is demonstrated to be the inter-diffusivity, (D) over tilde, of Ni and Al. The monovacancy-mediated LKMC1 simulation results are in good agreement with our 3-D APT data. The compositional interfacial width, for the (100)-interface, between the gamma(f.c.c.)- and gamma'(L1(2))-phases, decreases continuously with increasing aging time and < R(t)>, both for the 3-D APT results and the monovacancy-mediated LKMC1 simulations, in disagreement with an ansatz intrinsic to the trans-interface diffusion-controlled coarsening model, which assumes the exact opposite trend for binary alloys. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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