2021 IRG-1: Strengthening High Entropy Borides With Synergistic Boundary Segregation and Precipitation
High-entropy borides have shown dramatic strength increases with the addition of WB2 and/or MoB2. To uncover a physical explanation for this behavior, a new collaboration with Professors Jian Luo and Tim Rupert was developed.
The team discovered that W addition leads to simultaneous W segregation and W-rich precipitation at the grain boundaries. Similarly, W-Mo addition leads to W and Mo co-segregation and W-Mo-rich precipitates at the grain boundaries. The interfaces between the grain boundary precipitates and the matrix of the high-entropy borides are coherent, with a cube-on-cube orientation relationship. The synergistic grain boundary segregation and precipitation contributes a strengthening effect, as nanoindentation measurements near the boundaries were noticeably harder than the grain interiors, providing a pathway for ultra-strong high-temperature materials.
UCI MRSEC 2011967 IRG-1 Xin Boundary strengthening of borides.pptx
C Wang, M Qin, T Lei, Y He, K Kisslinger, TJ Rupert, J Luo, HL Xin, Synergic grain boundary segregation and precipitation in W-and W-Mo-containing high-entropy borides, Journal of the European Ceramic Society, https://doi.org/10.1016/j.jeurceramsoc.2021.04.004 (2021)
C Wang, T Lei, Y He, TJ Rupert, HL Xin (University of California, Irvine)
M Qin, J Luo (University of California, San Diego)