Effect of Sn microalloying on the nucleation of L12 Al3Zr precipitates in a dilute aluminum-zirconium alloy

Janet Meier; Dongwon Shin; Jonathan D. Poplawsky; Lawrence F. Allard; Huikai Cheng; Ichiro Ohnishi; Sumit Bahl; J. Allen Haynes; Nhon Q. Vo; Amit Shyam

doi:10.1016/j.jallcom.2025.180433

Effect of Sn microalloying on the nucleation of L1₂ Al₃Zr precipitates in a dilute aluminum-zirconium alloy

Janet Meier, Dongwon Shin, Jonathan D. Poplawsky, Lawrence F. Allard, Huikai Cheng, Ichiro Ohnishi, Sumit Bahl, J. Allen Haynes, Nhon Q. Vo, Amit Shyam

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

While L1₂-Al₃Zr nanoprecipitates provide a balance between strengthening and good electrical conductivity, the precipitation of L1₂-Al₃Zr in aluminum requires aggressive heat treatments. An improved age-hardening response was observed during isochronal aging of an Al-0.24Zr (wt%) alloy when microalloyed with Sn. A new mechanism termed Low melting point Element-Assisted Nucleation (LEAN) is proposed to explain the lower temperature nucleation of L1₂-Al₃Zr precipitates observed in this alloy based on the addition of a low melting point element, such as Sn. Characterization verified the first-principles density functional theory prediction that Zr and Sn atoms cluster during homogenization owing to the favorable binding energy of Zr-Sn-vacancy triplets. Direct microstructural observations revealed these clusters form Sn nanoprecipitates that assist the nucleation of L1₂-Al₃Zr at 200°C, where L1₂-Al₃Zr precipitation is not expected due to the low diffusivity of Zr atoms in Al. At higher temperatures (≳350°C), the acceleration of L1₂-Al₃Zr precipitation is driven by faster Zr diffusion in Al with Sn microalloying and the nuclei formed via the LEAN mechanism. This combination of mechanisms explains the improvement in age hardening through L1₂-Al₃Zr precipitation with Sn microalloying.

Original language	English
Article number	180433
Journal	Journal of Alloys and Compounds
Volume	1027
DOIs	https://doi.org/10.1016/j.jallcom.2025.180433
State	Published - May 10 2025

Funding

The research was sponsored by the Powertrain Materials Core Program under the Vehicle Technologies Office, US Department of Energy. The authors would also like to thank Dr. William Curtin (Brown Universiry), Dr. Roger Doherty (Drexel University), and Dr. Thomas R. Watkins (ORNL) for their insightful discussions. APT research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The authors would like to thank James Burns for assistance in performing APT sample preparation and running the APT experiments, Travis Dixon for expertise in preparation of thin-foil specimens for electron microscopy, Dana Mcclurg for collecting hardness and electrical conductivity measurements, and Ian Stinson and Dustin Heidel for preparation of alloys. This research used resources of the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. A portion of the research was performed using computational resources sponsored by the Department of Energy's Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory.

Keywords

Aluminum alloys
Atom probe
L1 trialuminide
Nucleation
Precipitation strengthening
STEM
Sn micro-alloying

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10.1016/j.jallcom.2025.180433

Cite this

@article{2240582b88d4405fb50d3efd92f8abc8,

title = "Effect of Sn microalloying on the nucleation of L12 Al3Zr precipitates in a dilute aluminum-zirconium alloy",

abstract = "While L12-Al3Zr nanoprecipitates provide a balance between strengthening and good electrical conductivity, the precipitation of L12-Al3Zr in aluminum requires aggressive heat treatments. An improved age-hardening response was observed during isochronal aging of an Al-0.24Zr (wt\%) alloy when microalloyed with Sn. A new mechanism termed Low melting point Element-Assisted Nucleation (LEAN) is proposed to explain the lower temperature nucleation of L12-Al3Zr precipitates observed in this alloy based on the addition of a low melting point element, such as Sn. Characterization verified the first-principles density functional theory prediction that Zr and Sn atoms cluster during homogenization owing to the favorable binding energy of Zr-Sn-vacancy triplets. Direct microstructural observations revealed these clusters form Sn nanoprecipitates that assist the nucleation of L12-Al3Zr at 200°C, where L12-Al3Zr precipitation is not expected due to the low diffusivity of Zr atoms in Al. At higher temperatures (≳350°C), the acceleration of L12-Al3Zr precipitation is driven by faster Zr diffusion in Al with Sn microalloying and the nuclei formed via the LEAN mechanism. This combination of mechanisms explains the improvement in age hardening through L12-Al3Zr precipitation with Sn microalloying.",

keywords = "Aluminum alloys, Atom probe, L1 trialuminide, Nucleation, Precipitation strengthening, STEM, Sn micro-alloying",

author = "Janet Meier and Dongwon Shin and Poplawsky, \{Jonathan D.\} and Allard, \{Lawrence F.\} and Huikai Cheng and Ichiro Ohnishi and Sumit Bahl and Haynes, \{J. Allen\} and Vo, \{Nhon Q.\} and Amit Shyam",

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month = may,

day = "10",

doi = "10.1016/j.jallcom.2025.180433",

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T1 - Effect of Sn microalloying on the nucleation of L12 Al3Zr precipitates in a dilute aluminum-zirconium alloy

AU - Meier, Janet

AU - Shin, Dongwon

AU - Poplawsky, Jonathan D.

AU - Allard, Lawrence F.

AU - Cheng, Huikai

AU - Ohnishi, Ichiro

AU - Bahl, Sumit

AU - Haynes, J. Allen

AU - Vo, Nhon Q.

AU - Shyam, Amit

PY - 2025/5/10

Y1 - 2025/5/10

N2 - While L12-Al3Zr nanoprecipitates provide a balance between strengthening and good electrical conductivity, the precipitation of L12-Al3Zr in aluminum requires aggressive heat treatments. An improved age-hardening response was observed during isochronal aging of an Al-0.24Zr (wt%) alloy when microalloyed with Sn. A new mechanism termed Low melting point Element-Assisted Nucleation (LEAN) is proposed to explain the lower temperature nucleation of L12-Al3Zr precipitates observed in this alloy based on the addition of a low melting point element, such as Sn. Characterization verified the first-principles density functional theory prediction that Zr and Sn atoms cluster during homogenization owing to the favorable binding energy of Zr-Sn-vacancy triplets. Direct microstructural observations revealed these clusters form Sn nanoprecipitates that assist the nucleation of L12-Al3Zr at 200°C, where L12-Al3Zr precipitation is not expected due to the low diffusivity of Zr atoms in Al. At higher temperatures (≳350°C), the acceleration of L12-Al3Zr precipitation is driven by faster Zr diffusion in Al with Sn microalloying and the nuclei formed via the LEAN mechanism. This combination of mechanisms explains the improvement in age hardening through L12-Al3Zr precipitation with Sn microalloying.

AB - While L12-Al3Zr nanoprecipitates provide a balance between strengthening and good electrical conductivity, the precipitation of L12-Al3Zr in aluminum requires aggressive heat treatments. An improved age-hardening response was observed during isochronal aging of an Al-0.24Zr (wt%) alloy when microalloyed with Sn. A new mechanism termed Low melting point Element-Assisted Nucleation (LEAN) is proposed to explain the lower temperature nucleation of L12-Al3Zr precipitates observed in this alloy based on the addition of a low melting point element, such as Sn. Characterization verified the first-principles density functional theory prediction that Zr and Sn atoms cluster during homogenization owing to the favorable binding energy of Zr-Sn-vacancy triplets. Direct microstructural observations revealed these clusters form Sn nanoprecipitates that assist the nucleation of L12-Al3Zr at 200°C, where L12-Al3Zr precipitation is not expected due to the low diffusivity of Zr atoms in Al. At higher temperatures (≳350°C), the acceleration of L12-Al3Zr precipitation is driven by faster Zr diffusion in Al with Sn microalloying and the nuclei formed via the LEAN mechanism. This combination of mechanisms explains the improvement in age hardening through L12-Al3Zr precipitation with Sn microalloying.

KW - Aluminum alloys

KW - Atom probe

KW - L1 trialuminide

KW - Nucleation

KW - Precipitation strengthening

KW - STEM

KW - Sn micro-alloying

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