Atomic-resolution observations combined with simulations show that grain boundaries within elemental copper undergo temperature-induced solid-state phase transformation to different structures
grain boundary phases can also coexist and are kinetically trapped structures.
The theory of grain boundary (the interface between crystallites, GB) structure has a long history(1) and the concept of GBs undergoing phase transformations was proposed 50 years ago(2,3). The underlying assumption was that multiple stable and metastable states exist for different GB orientations(4-6). The terminology '
