  Computing the grain boundary (GB) counterparts to bulk phase diagrams
represents an emerging research direction with potentially broad impacts. Using
a classical embrittlement model system Ga-doped Al, this study demonstrates the
feasibility of computing temperature- and composition-dependent GB diagrams to
represent not only equilibrium thermodynamic and structural characters, but
also mechanical properties. Specifically, hybrid Monte Carlo and molecular
dynamics (MC/MD) simulations are used to obtain the equilibrium GB structure as
a function of temperature and composition. Simulated GB structures are
validated by aberration-corrected scanning transmission electron microscopy.
Subsequently, MD tensile tests are performed on the simulated equilibrium GB
structures. GB diagrams are computed for not only GB adsorption and disorder,
but also interfacial structural and chemical widths, MD ultimate strength, and
tensile toughness. A model is established to forecast the ductile-to-brittle
transition. This study establishes a new paradigm to compute a spectrum of GB
diagrams to enable the investigation of the unique GB
composition-structure-property relationship.
