Abstract

The evolution of rapid solidification (RS) microstructure and solidification interface velocity has been studied experimentally by in-situ transmission electron microscopy and postmortem characterization for hypereutectic Al-20at.%Cu (37 wt.%Cu) after laser melting. Four morphologically distinct regions formed via growth modes changing from θ-Al₂Cu phase dendrites to eutectic cell growth, possibly α-Al dendrite growth (α-cell), banded growth, and α-Al plane front growth. Tendency for faceting and low capacity for solute trapping limited the θ-phase dendrite growth to solidification interface velocity v < 0.07 m/s. Consequently, formation of pro-eutectic micro-constituent was suppressed, and RS microstructure formation was dominated by eutectic, α-cell, and banded morphology grains for the Al-20at.%Cu alloy. Eutectic growth operated for interface velocity of 0.1 m/s ≤ v < 0.3 m/s, with a transition from regular lamellar, 2-λ and 1-λ mode to a dense irregular morphology dominated by α-phase at v = 0.3 m/s. Interface temperature calculations indicated feasibility of α-cell growth mode for 0.3 m/s ≤ v < 0.7 m/s. Banded growth occurred for 0.7 m/s ≤ v < 1.3 m/s. Plane front α-phase growth was evident for interface velocities v ≥ 1.3 m/s. Previous work on rapid solidification microstructure development in hypereutectic Al-Cu alloys reported a regime of α-cellmore » growth subsequently to eutectic and prior to transition to banded growth for Al-19at.%Cu (36 wt.%Cu), while for Al-22at.%Cu (40 wt.%Cu) eutectic growth transitioned directly to α-plane front growth without emergence of a banded regime. Finally, based on the current study the disappearance of the banded growth regime occurs for a composition larger than 20at.%Cu.« less

Authors:

Liu, Y.  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-3415-4756"

Zweiacker, K.  ^[2];

• Search DOE PAGES for author "Zweiacker, K."
• Search DOE PAGES for ORCID "0000-0002-4365-7374"

Liu, C. ^[1]; McKeown, J. T. ^[3]; Wiezorek, J. M. K.  ^[1]

• Search DOE PAGES for author "Wiezorek, J. M. K."
• Search DOE PAGES for ORCID "0000-0002-1358-0556"

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+ Show Author Affiliations

1. Univ. of Pittsburgh, PA (United States)
2. Univ. of Pittsburgh, PA (United States); Hitachi Energy, Zürich (Switzerland)
3. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Publication Date:

Fri Nov 03 00:00:00 EDT 2023

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)

OSTI Identifier:

2281477

Report Number(s):

LLNL-JRNL-859079
Journal ID: ISSN 1359-6454; 1089742

Grant/Contract Number:  

AC52-07NA27344

Resource Type:

Accepted Manuscript

Journal Name:

Acta Materialia

Additional Journal Information:

Journal Volume: 263; Journal ID: ISSN 1359-6454

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Rapid solidification; Laser melting; Solute trapping; Microstructure; Interface velocity; TEM