Icosahedral Ti-Zr-Ni: A groundstate quasicrystal?

Abstract

The first complete ab initio zero-temperature ternary phase diagram is constructed from the calculated energies of the elemental, binary and ternary Ti-Zr-Ni phases; for this, the icosahedral i-TiZrNi quasicrystal phase is approximated by periodic structures of up to 123 atoms/unit cell, based on a decorated-tiling model. The approximant structures containing the 45-atom Bergman cluster were nearly degenerate, and stable against the competing binary phases. It is speculated that i-TiZrNi may be a ground state quasicrystal, as it is experimentally the low-temperature phase for its composition.