We show that chemistry can be used to trigger a nanofaceting transition. In particular, the segregation of Ag to an asymmetric tilt grain boundary in Cu is investigated. Aberration-corrected electron microscopy reveals that annealing the bicrystal results in the formation of nanometer-sized facets composed of preferentially Ag-segregated symmetric $\mathrm{\Sigma }5\{210\}$ segments and Ag-depleted $\{230\}/\{100\}$ asymmetric segments. Our observations oppose an anticipated trend to form coarse facets. Atomistic simulations confirm the nanofacet formation observed in the experiment and demonstrate a concurrent grain boundary phase transition induced by the anisotropic segregation of Ag.

• Received 28 May 2018
• Revised 23 October 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.255502

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Published by the American Physical Society