Revealing the Origin of Heterogeneous Phase Transition and Deformation Behavior in Au-Ag-Cu-Based Multicomponent Alloys

Local chemical heterogeneity of highly-concentrated multicomponent alloys has drawn much attention as it can produce novel material behaviors and remarkable properties. In Au-Ag-Cu-based multicomponent alloys, phase separation and ordering have long been recognized to correlate with grain boundaries...

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Bibliographic Details
Published inMetals (Basel ) Vol. 12; no. 11; p. 1966
Main Authors Zhang, Boning, Fu, Li, Ge, Hualong, Rong, Xuequan, Xiong, Kai, He, Junjie, Mao, Yong
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.11.2022
Subjects
Alloys
Analysis
Atoms & subatomic particles
Copper
Copper base alloys
Deformation
Depletion
Equilibrium
First principles
Force and energy
Gold
Grain boundaries
Heterogeneity
Lamellar structure
Mechanical properties
Microscopy
multicomponent alloys
Nanoelectromechanical systems
Nanoparticles
Nanotechnology
Noble metals
Nucleation
Phase composition
Phase separation
phase transition
Phase transitions
Silver
Specialty metals industry
Stacking faults
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Summary:Local chemical heterogeneity of highly-concentrated multicomponent alloys has drawn much attention as it can produce novel material behaviors and remarkable properties. In Au-Ag-Cu-based multicomponent alloys, phase separation and ordering have long been recognized to correlate with grain boundaries (GBs), but there is still a lack of atomic-scale understanding of the heterogeneous phase transition and how the microstructures respond to deformation. In this paper, a joint experimental and theoretical study was conducted on a medium-entropy polycrystalline model alloy, which is a representative Au-Ag-Cu-based multicomponent alloy with important applications in fields such as photocatalyst and micro-/nano-electromechanical systems. The GB regions are observed to preferentially nucleate two-phase lamellar structures, which are softer than grain interiors featuring short-range-order and modulated morphologies. First-principles calculations suggest the GB segregation of Ag and depletion of Cu are energetically favorable, consequently creating compositions that facilitate phase separation and impede ordering. Calculations of elasticity-based mechanical properties, stacking fault and surface energies reveal the GB lamellar structures are intrinsically soft with heterogeneous deformation capabilities. Furthermore, design strategies based on GB segregation engineering and tuning the dual-phase compositions are proposed to control heterogeneities. The results provide new insights into GB segregation, phase nucleation precursor and mechanical properties of noble-metal multicomponent alloys.
ISSN:2075-4701
2075-4701
DOI:10.3390/met12111966