Phase stabilities in the AlCuRu system

Isothermal sections of the AlCuRu phase diagram at 500 and 800dgC have been determined for Al concentrations greater than 60 at.%. At 500°C, the icosahedral phase is not thermodynamically stable, whereas at 800°C it is stable over a fairly broad compositional region. The formation of the fci phase from the low temperature tetragonal phase is by a nucleation and growth process. The first-order transformation to the fci phase is endothermic, indicating that the fci phase is at a higher energy than the tetragonal phase.