Synergic grain boundary segregation and precipitation in W- and W-Mo-containing high-entropy borides |
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| Authors: | Chunyang Wang Mingde Qin Tianjiao Lei Yubin He Kim Kisslinger Timothy J Rupert Jian Luo Huolin L Xin |
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| Affiliation: | 1. Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA;2. Department of NanoEngineering, Program of Materials Science and Engineering, University of California, San Diego, La Jolla, CA, 92093, USA;3. Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA;4. Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA, 92697, USA;5. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, 11973, USA |
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| Abstract: | The structures of W- and W-Mo-containing high-entropy borides (HEBs) are systematically studied by combining atomic-resolution transmission electron microscopy imaging, electron diffraction, and chemical analysis. We reveal that W or W-Mo addition in HEBs leads to segregation of these elements to the grain boundaries (GBs). In the meantime, W- or W-Mo-rich precipitates also form along the GBs. Crystallographic analysis and atomic-scale imaging show that the GB precipitates in both W- and W-Mo-containing HEBs have a cube-on-cube orientation relationship with the matrix. With further strain analysis, the coherency of the precipitate/matrix interface is validated. Nanoindentation tests show that the simultaneous GB segregation and coherent precipitation, as a supplement to the grain hardening, provide additional hardening of the HEBs. Our work provides an in-depth understanding of the GB segregation and precipitation behaviors of HEBs. It suggests that GB engineering could be potentially used for optimizing the performance of high-entropy ceramics. |
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| Keywords: | High-entropy ceramics High-entropy borides Grain boundary Segregation Precipitation |
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