Growth modes of grain boundary precipitate in aluminum alloys under different lattice misfits

The properties of aluminum alloys are profoundly affected by a rich variety of precipitates. Their precipitation behaviors are often very different from each other due to a wide range of lattice misfits between the precipitates and the matrix. This makes the study of mechanisms of the formation of a...

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Bibliographic Details
Published in:	Journal of materials science 2022, Vol.57 (4), p.2744-2757
Main Authors:	Shuai, X., Mao, H., Tang, S., Kong, Y., Du, Y.
Format:	Article
Language:	eng
Subjects:	Aluminum Aluminum alloys Aluminum base alloys Analysis Characterization and Evaluation of Materials Chemical precipitation Chemistry and Materials Science Classical Mechanics Computation & Theory Crystallography and Scattering Methods Grain boundaries Growth Island growth Lattice vibration Materials Science Nickel Nucleation Nuclei Polymer Sciences Precipitates Solid Mechanics Specialty metals industry Spinodal decomposition
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Summary:	The properties of aluminum alloys are profoundly affected by a rich variety of precipitates. Their precipitation behaviors are often very different from each other due to a wide range of lattice misfits between the precipitates and the matrix. This makes the study of mechanisms of the formation of aluminum alloy precipitates very complex and often controversial. Here, the phase-field crystal methodology is used to study grain boundary (GB) precipitation under different lattice misfits. We find that the growth mode of GB precipitation changes from island growth mode to layer growth mode with increasing lattice misfit. At a relatively low lattice misfit, GB segregation and spinodal decomposition first lead to the heterogeneous distribution of solute and then nucleation events at solute-enriched sites, which is conducive to the island growth of the nuclei. In contrast, at a sufficiently high lattice misfit, a layer with a high solute concentration is formed soon along the entire GB due to a great amount of solute segregation, which gives rise to the rapid merging of densely distributed nuclei, and then layer growth occurs. Quantitative analysis reveals that the increase in lattice misfit decreases the nucleation barrier and the critical concentration required by the onset of structural transformation. Our study contributes to a systematic understanding of the formation of diversified precipitates in aluminum alloys in terms of lattice misfit. Graphical abstract
ISSN:	0022-2461 1573-4803