Formation of a single Al-Co-Ni quasicrystal upon collision of multiple grains

Quasicrystals are solids that have long-range orientational order but lack translational periodicity. These materials are of significant interest as they possess mechanical and transport properties typically not observed in periodically crystalline materials with similar compositions. However, experimental fabrication of defect-free quasicrystals poses a significant barrier to commercial applications. It is critical to understand how conventional strain (phonon strain) and phason strain, which is unique to quasicrystals, contribute to grain boundary formation and grain coalescence. We present a joint experimental-computational study where we elucidate the contributions of phasons to grain coalescence mechanisms in Al-Co-Ni quasicrystals, and investigate the effects of initial misorientation on the formation of grain boundaries. Our study reveals how the unique symmetries of quasicrystals govern grain coalescence, providing a novel handle that can be used to design defect-free fabrication of quasicrystalline materials.