Abstract
Control of the atomic structure, as measured by the extent of the embrittling B2 chemically ordered phase, is demonstrated in intermetallic alloys through additive manufacturing (AM) and characterized using high fidelity neutron diffraction. As a layer-by-layer rapid solidification process, AM was employed to suppress the extent of chemically ordered B2 phases in a soft ferromagnetic Fe-Co alloy, as a model material system of interest to electromagnetic applications. The extent of atomic ordering was found to be insensitive to the spatial location within specimens and suggests that the thermal conditions within only a few AM layers were most influential in controlling the microstructure, in agreement with the predictions from a thermal model for welding. Analysis of process parameter effects on ordering found that suppression of B2 phase was the result of an increased average cooling rate during processing. AM processing parameters, namely interlayer interval time and build velocity, were used to systematically control the relative fraction of ordered B2 phase in specimens from 0.49 to 0.72. Hardness of AM specimens was more than 150% higher than conventionally processed bulk material. Implications for tailoring microstructures of intermetallic alloys are discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 772-780 |
| Number of pages | 9 |
| Journal | Additive Manufacturing |
| Volume | 28 |
| DOIs | |
| State | Published - Aug 2019 |
Funding
The authors acknowledge Chad Taylor, Christina Profazi, Alice Kilgo, Bonnie McKenzie, and Sara Dickens for specimen preparation and microstructure characterization. The authors also wish to thank Dr. Michael Heiden for internal peer-review of this manuscript prior to submission. This research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory (proposal IPTS 20877) on the HB-2B beamline. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. A portion of this research was sponsored by the Sandia National Laboratories Laboratory Directed Research and Development Program . Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. 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, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).
| Funders | Funder number |
|---|---|
| Sandia National Laboratories Laboratory Directed Research and Development Program | |
| U.S. Department of Energy | |
| National Nuclear Security Administration | DE-NA0003525 |
Keywords
- Additive manufacturing
- Atomic ordering
- Disorder-order transformation
- Fe-Co alloys
- Hall-Petch strengthening
- Hardness
- Intermetallic alloys
- Microstructure
- Rapid solidification
- Soft magnetic alloys
- Thermal measurements
