Phase transformation of quasicrystals in aluminium-transition metal alloys

Abstract

Quasicrystals in Al–Mn, Al–Cu–TM (TM = Fe, Cr, Mn and Ru) and Al–Cu–Fe–Cr alloys can undergo two different modes of phase transformation. Discontinuous transformations of quasicrystals are characterized by the existence of a definite reaction front separating the quasicrystalline phase from the resulting crystalline one; the kinetics are controlled by the migration of the reaction front. Continuous transitions, on the other hand, proceed by structural evolution such as modulation or chemical ordering inside the quasicrystalline phase without creating any high-energy interfaces. Both types of transformations are thermally activated and need atomic diffusion.

Key Words:

• Phase transformation
• quasicrystals
• thermodynamics
• kinetics
• diffusion
• electron microscopy