Microstructure and mechanical properties of hypoeutectic Al–6Ce–3Ni-0.7Fe (wt.%) alloy

Tiffany Wu, Alex Plotkowski, Amit Shyam, David C. Dunand

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

A hypoeutectic, Fe-modified Al–Ce–Ni alloy (Al–6Ce–3Ni-0.7Fe, wt.%) is studied in terms of microstructure, thermal stability, ambient temperature strengthening, and creep resistance. The as-cast microstructure consists of primary Al dendrites and interdendritic binary eutectic regions (Al–Al11Ce3 and/or Al–Al9(Fe,Ni)2), with micron/submicron lamellar spacing, depending on the location along the height of the ingot. The cast alloy exhibits excellent coarsening resistance at 400 °C, with mostly unchanged microstructure and microhardness after 6 weeks of aging, indicating good thermal stability of Al11Ce3 and Al9(Fe,Ni)2. Orowan strengthening and load transfer are identified as strengthening mechanisms at ambient and elevated temperature. A high volume fraction of the intermetallic phases (providing load transfer) and relatively coarse eutectic spacing (for modest Orowan strengthening) result in a moderate as-cast microhardness of 566 ± 32 MPa. Creep resistance at 300 and 350 °C is similar to a binary Al-12.5Ce eutectic alloy (with twice the Ce content) because of two countering effects: Al–6Ce–3Ni-0.7Fe shows a higher volume fraction of strengthening intermetallic phases, but it also exhibits a large fraction of primary Al dendrites which weaken the alloy. By contrast, the alloy, when laser-remelted at the surface, has a fully eutectic microstructure without primary aluminum dendrites achieved by high undercooling on solidification, with a refined network of eutectic phases that doubles the microhardness as compared to the cast alloy. Whereas coarsening is faster due to the shorter diffusion distances between the eutectic phases, hardness remains ∼30% higher than the as-cast alloy after ∼6 weeks aging at 400 °C.

Original languageEnglish
Article number145072
JournalMaterials Science and Engineering: A
Volume875
DOIs
StatePublished - Jun 6 2023

Funding

TW was supported by the GO! Program from Oak Ridge National Laboratory (ORNL). This research was co-sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office and Vehicle Technologies Office Propulsion Materials Program (AP and AS). This work made use of the Materials Characterization and Imaging Facility and EPIC facility of Northwestern University's NUANCE Center, which both receive support from the MRSEC Program ( NSF DMR-1720139 ) of the Materials Research Center at Northwestern University. X-ray diffraction was conducted by Dr. C.M. Fancher (ORNL) as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at ORNL. Mr. F.M. Carter (Northwestern University) is gratefully acknowledged for experimental support with the laser-remelting trials, which were performed at the CHiMad Metals Processing Facility at Northwestern University (CHiMad is supported by the U.S. Department of Commerce , National Institute of Standards and Technology , under award 70NANB14H012 ). The authors thank Dr. J. Meier (ORNL) and Dr. M. Kesler (ORNL) for the reviews. Notice: This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (https://www.energy.gov/downloads/doe-public-access-plan). TW was supported by the GO! Program from Oak Ridge National Laboratory (ORNL). This research was co-sponsored by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office and Vehicle Technologies Office Propulsion Materials Program (AP and AS). This work made use of the Materials Characterization and Imaging Facility and EPIC facility of Northwestern University's NUANCE Center, which both receive support from the MRSEC Program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. X-ray diffraction was conducted by Dr. C.M. Fancher (ORNL) as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at ORNL. Mr. F.M. Carter (Northwestern University) is gratefully acknowledged for experimental support with the laser-remelting trials, which were performed at the CHiMad Metals Processing Facility at Northwestern University (CHiMad is supported by the U.S. Department of Commerce, National Institute of Standards and Technology, under award 70NANB14H012). The authors thank Dr. J. Meier (ORNL) and Dr. M. Kesler (ORNL) for the reviews.

Keywords

  • Aluminum alloys
  • Coarsening
  • Compressive creep
  • Laser-remelting
  • Microhardness

Fingerprint

Dive into the research topics of 'Microstructure and mechanical properties of hypoeutectic Al–6Ce–3Ni-0.7Fe (wt.%) alloy'. Together they form a unique fingerprint.

Cite this