Atomistic investigation of clustering phenomenon in the Al–Cu system: Three-dimensional phase-field crystal simulation and HRTEM/HRSTEM characterization

Fallah, Vahid; Korinek, Andreas; Ofori-Opoku, Nana; Provatas, Nikolas; Esmaeili, Shahrzad

doi:10.1016/j.actamat.2013.07.015

Cited by 42 publications

(42 citation statements)

References 36 publications

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“…The descriptions of such methodologies can be found in detail in Refs. 40,41,43 . Below, we present the details of the above PFC calculations and simulation methodologies for clustering in a ternary alloy system in 3D.…”

Section: Model Structurementioning

confidence: 99%

“…The simulation of clustering is carried out applying dissipative dynamics to the PFC free energy functions while introducing quenched-in dislocations 40,41,43 into a single-phase (Al) domain of A1 and A2 alloy compositions held at σ = 0. A low amplitude stochastic noise is introduced to both density and concentration fields to simulate stochastic fluctuations that can potentially be required to stimulate nucleation.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…As also documented in Refs. 40,41,43 , the mean-field approximations of PFC free energy was carried out following the procedure detailed in ref. 39 .…”

Section: Model Structurementioning

confidence: 99%

“…Using the PFC approach, Fallah et al 41,43 , for the first time, analyzed atomistic transformations and the full free energy-based path leading to the earliest stage precipitation in the presence of quenched-in and mobile dislocations in the Al-Cu-(Mg) alloy system. They also used high resolution transmission and scanning-transmission electron microscopy (HRTEM and HRSTEM, respectively) methods to assess the 3D atomic-scale simulation results through direct observation of clustering that occurs during natural aging in the Al-Cu system 40 . That study well demonstrated the validity of the simulated dislocation-induced early-stage clustering phenomena and the preferred orientation of the early clusters on the FCC closed packed (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…The aim of this work is to move a major step forward in filling an important gap in this knowledge through both atomic-scale observations and computational modelling. The computational approach is based on the recently-developed modeling paradigm, known as the Phase Field Crystal (PFC) methodology [35][36][37][38][39] , which has shown a remarkable capacity in capturing the salient physics of diffusional phase transitions involving atomic scale elastic and plastic interactions [40][41][42][43] . Using the PFC approach, Fallah et al 41,43 , for the first time, analyzed atomistic transformations and the full free energy-based path leading to the earliest stage precipitation in the presence of quenched-in and mobile dislocations in the Al-Cu-(Mg) alloy system.…”

Section: Introductionmentioning

confidence: 99%

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Atomic-scale pathway of early-stage precipitation in Al–Mg–Si alloys

et al. 2015

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Strengthening in age-hardenable alloys is mainly achieved through nano-scale precipitates whose formation paths from the atomic-scale, solute-enriched entities are rarely analyzed and understood in a directly-verifiable way. Here, we discover a pathway for the earliest-stage precipitation in Al-Mg-Si alloys: solute clustering leading to three successive variants of FCC clusters, followed by the formation of non-FCC GP -zones. The clusters, which originally assume a spherical morphology (C1), evolve into elongated clusters and orient themselves on {111} Al (C2) and subsequently on {100} Al planes and <100> Al directions (C3). We also analyze the association of quenched-in dislocations with clustering phenomena. The results of this work can open a new frontier in advancing alloy-process-property design for commercially-important age-hardenable Al alloys.

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Section: Model Structurementioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

“…As also documented in Refs. 40,41,43 , the mean-field approximations of PFC free energy was carried out following the procedure detailed in ref. 39 .…”

Section: Model Structurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Atomic-scale pathway of early-stage precipitation in Al–Mg–Si alloys

et al. 2015

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Structure and growth of core–shell nanoprecipitates in Al–Er–Sc–Zr–V–Si high-temperature alloys

et al. 2018

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Lightweight Sc-containing aluminum alloys exhibit superior mechanical performance at high temperatures due to core-shell, L12-ordered trialuminide nanoprecipitates. In this study, the structure of these nanoprecipitates was studied, using different transmission electron microscopy (TEM) techniques, for an Al-Er-Sc-Zr-V-Si alloy that was subjected to a two-stage overaging heat treatment. Energy-dispersive X-ray spectroscopy of the spherical Al3(Sc, Zr, Er ,V) nanoprecipitates revealed a core-shell structure with an Sc-and Er-enriched core and a Zr-enriched shell, without a clear V outer shell. This structure is stable up to 72% of the absolute melting temperature of Al for extended periods of time. High-angle annular dark-field scanning TEM was used to image the {100} planes of the nanoprecipitates, demonstrating a homogeneous L12-ordered superlattice structure for the entire nanoprecipitates, despite the variations in the concentrations of solute atoms within the unit cells. A possible growth path and compositional trajectory for these nanoprecipitates was proposed using highresolution TEM observations, where different rod-like structural defects were detected, which are considered to be precursors to the spherical L12-ordered nanoprecipitates. It is also hypothesized that the structural defects could consist of segregated Si; however, this was not possible to verify with HAADF-STEM because of the small differences in Al and Si atomic numbers. The results herein allow a better understanding of how the Al-Sc alloys' core-shell nanoprecipitates form and evolve temporally, thereby providing a better physical picture for future atomistic structural mappings and simulations.

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Atomic-scale study of compositional and structural evolution of early-stage grain boundary precipitation in Al–Cu alloys through phase-field crystal simulation

et al. 2021

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Interfacial solute clustering is an essential step preceding grain boundary (GB) precipitation. Both states, i.e., clusters and precipitates, alter the mechanical, chemical, and corrosion properties of materials. Continuum models cannot capture the atomic details of these phenomena, specifically of the transition from clustering to precipitation. We thus use the structural phase-field crystal (XPFC) model to study the compositional and structural evolution during GB clustering in Al-Cu alloys. The results show that the compositional evolution is dominated by solute segregation to lattice defects at the very beginning and then by confined spinodal decomposition along the GBs. The latter leads to a steep increase in the concentration and then the formation of disordered clusters. This structure acts as a precursor for phase nucleation, just like the decomposed solid solution, and Guinier-Preston zones are the precursors of the thermodynamically stable Al 2 Cu phase in the interior of grains. Two modes of spinodal decomposition are found. (a) On low-angle tilt GBs, spinodal decomposition occurs at the dislocations that constitute the GB. (b) On high-angle tilt GBs, spinodal decomposition takes place inside the entire GB plane. In either case, the structural transition from the disordered low-dimensional precursor states to an ordered phase state takes place following the compositional enrichment. These results shed light on atomic-scale early-stage GB decomposition and precipitation processes in Al-Cu alloys and enrich our knowledge about the coupling effects between compositional and structural evolution during GB phase transformation phenomena.

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Atomistic investigation of clustering phenomenon in the Al–Cu system: Three-dimensional phase-field crystal simulation and HRTEM/HRSTEM characterization

Cited by 42 publications

References 36 publications

Atomic-scale pathway of early-stage precipitation in Al–Mg–Si alloys

Atomic-scale pathway of early-stage precipitation in Al–Mg–Si alloys

Structure and growth of core–shell nanoprecipitates in Al–Er–Sc–Zr–V–Si high-temperature alloys

Atomic-scale study of compositional and structural evolution of early-stage grain boundary precipitation in Al–Cu alloys through phase-field crystal simulation

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