  Dislocation and grain boundary melting are studied in three dimensions using
the Phase Field Crystal method. Isolated dislocations are found to melt
radially outward from their core, as the localized excess elastic energy drives
a power law divergence in the melt radius. Dislocations within low-to-mid angle
grain boundaries melt similarly until an angle-dependent first order wetting
transition occurs when neighboring melted regions coalesce. High angle
boundaries are treated within a screening approximation, and issues related to
ensembles, metastability, and grain size are discussed.
