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Duplex nanocrystalline alloys: Entropic nanostructure stabilization and a case study on W-Cr
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Document Title
Duplex nanocrystalline alloys: Entropic nanostructure stabilization and a case study on W-Cr
Author
Chookajorn T., Park M., Schuh C.A.
Name from Authors Collection
Affiliations
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States; National Metal and Materials Technology Center, National Science and Technology Development Agency, PathumThani, 12120, Thailand
Type
Article
Source Title
Journal of Materials Research
ISSN
08842914
Year
2014
Volume
30
Issue
2
Page
151-163
Open Access
All Open Access, Green
Publisher
Cambridge University Press
DOI
10.1557/jmr.2014.385
Format
Abstract
Grain boundary (GB) segregation can markedly improve the stability of nanostructured alloys, where the fraction of GB sites is inherently large. Here, we explore the concept of entropically supported GB segregation in alloys with a tendency to phase-separate and its role in stabilizing nanostructures therein. These duplex nanocrystalline alloys are notably different, both in a structural and thermodynamic sense, from the previously studied classical nanocrystalline alloys, which are solid solutions with GB segregation of solute. Experiments are conducted on the W-Cr system, in which nanoduplex structures are expected. Upon heating ball-milled W-15 at.% Cr up to 950 °C, a nanoscale Cr-rich phase was found along the GBs. These precipitates mostly dissolved into the W-rich grains leaving behind Cr-enriched GBs upon further heating to 1400 °C. The presence of Cr-rich nanoprecipitates and GB segregation of Cr is in line with prediction from our Monte Carlo simulation when GB states are incorporated into the alloy thermodynamics. © 2015 Materials Research Society.
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Publication Source
Scopus