Stability of binary nanocrystalline alloys against grain growth and phase separation

By H. Murdoch, C. A. Schuh. 2013

246 citations recorded by the source corpus.

Abstract Grain boundary segregation has been established through both simulation and experiments as a successful approach to stabilize nanocrystalline materials against grain growth. However, relatively few alloy systems have been studied in this context; these vary in their efficacy, and in many cases the stabilization effect is compromised by second phase precipitation. Here we address the open-ended design problem of how to select alloy systems that may be stable in a nanocrystalline state. We continue the development of a general “regular nanocrystalline solution” model to identify the conditions under which binary nanocrystalline alloy systems with positive heats of mixing are stable with respect to both grain growth (segregation removes the grain boundary energy penalty) and phase separation (the free energy of the nanocrystalline system is lower than the common tangent defining the bulk miscibility gap). We calculate a “nanostructure stability map” in terms of alloy thermodynamic parameters. Three main regions are delineated in these maps: one where grain boundary segregation does not result in a stabilized nanocrystalline structure, one in which macroscopic phase separation would be preferential (despite the presence of a nanocrystalline state stable against grain growth) and one for which the nanocrystalline state is stable against both grain growth and phase separation. Additional details about the stabilized structures are also presented in the map, which can be regarded as a tool for the design of stable nanocrystalline alloys.

Subfields: Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/0a64ad7c178c265249ce0a40b45c56a116c4c5ce

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Materials Chemistry

1. I. Ovid’ko
2. Yuntian Zhu
3. R. Valiev
4. H. Peng
5. F. Liu
6. M. Gong
7. Y. Z. Chen
8. R. Andrievski

In Mechanical Engineering

1. Yuntian Zhu
2. I. Ovid’ko
3. R. Valiev
4. H. Peng
5. F. Liu
6. M. Gong
7. Y. Z. Chen
8. R. Andrievski

Citations in the corpus

• Review of thermal stability of nanomaterials (2014, background): “The key breakthrough of these studies was to apply the usual, regular solution approximation to both bulk and grain-boundary regions of nanocrystals, and thus derive an expression for DG of alloy A(solvent)–B(solution) [19, 20]:”
• Segregation-induced changes in grain boundary cohesion and embrittlement in binary alloys (2015, unknown): “Such a formulation is analogous to that used in several previous treatments of nanocrystalline stability [39-44], but has not previously been used to examine free surface effects or embrittlement.”
• Thermal stability of nanocrystalline materials: thermodynamics and kinetics (2017, methodology): “[109] and applied to systems with a positive mixing enthalpy by Murdoch and Schuh [28] and ternary”
• Review on superior strength and enhanced ductility of metallic nanomaterials (2018, background): “Alloy systems reported with full thermodynamic stabilization include Ti-W and Al-Pb [484,487].”