EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The goal of this work is the observations of grain boundary phase transformations in Al and Cu-based alloys with the aid of differential scanning calorimetry. High-pressure torsion has been used to obtain the ultra-fine grained state with a high specific area of grain boundaries in Al–Zn, Al–Mg, Cu–Ag, Cu–Co, and Cu–Ni solid solutions with face-centered cubic (fcc) lattices. The ultra-fine grained samples were heated in a differential scanning calorimeter. Small endothermic peaks in the differential scanning calorimeter curves were observed in the one-phase solid-solution area of the respective phase diagrams, i.e., far away from the bulk solidus and solvus lines. A possible explanation of these endothermic peaks is based on the hypothesis of phase transformations between grain boundary complexions. This hypothesis has been supported by observations with transmission electron microscopy and electron backscattering diffraction. The new lines of grain boundary phase transformations have been constructed in the Al–Zn, Al–Mg, Cu–Ag, Cu–Co, and Cu–Ni bulk phase diagrams.