Segregation-Induced Nanofaceting Transition at an Asymmetric Tilt Grain Boundary in Copper

Nicolas J Peter,Raheleh Hadian,Maria J Duarte,Christoph Kirchlechner,Christian H Liebscher,Gerhard Dehm,Timofey Frolov,Colin Ophus

doi:10.1103/physrevlett.121.255502

Abstract

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 Σ5{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.

Highlights

Grain boundaries (GBs), as internal interfaces in polycrystals, strongly influence many properties of structural and functional materials [1]
Temperatureinduced GB faceting was reported in experimental studies [15,16,17] and facet formation mechanisms were explored by atomistic simulations in single component systems [18,19,20,21,22]
In this Letter we use atomic resolution scanning transmission electron microscopy (STEM), atom probe tomography (APT), and atomistic simulations to Published by the American Physical Society demonstrate a nanoscale faceting transition in an asymmetric Cu tilt grain boundary induced by segregation of Ag

Summary

Introduction

Grain boundaries (GBs), as internal interfaces in polycrystals, strongly influence many properties of structural and functional materials [1]. The new GB plane orientation was close to f110g=f310g, which is only a few degrees away from the as-grown state, confirming the inclinational isotropy of the GB energy in pure Cu. Very different behavior was observed in the sample doped with Ag. After annealing, the GB distinctly faceted at the atomic scale into an asymmetric segment close to f230g= f100g, and a symmetric Σ5 f210g segment [Fig. 1(c)].

Results

Conclusion