On the Phase Transformation of Bulk as-Cast Ti40Zr40Ni20 Quasicrystal

Abstract:

A pure quasicrystal with the composition Ti40Zr40Ni20 was obtained in bulk form by using conventional suction-casting. The quasi-lattice constant of the icosahedral phase (I-phase) is 0.523 nm. Differential scanning calorimetry (DSC) together with X-ray diffraction were used to study the temperature-induced phase transformation of the as-cast I-phase. Two endothermic reactions are identified in the DSC trace. The first endothermic reaction with an onset temperature of 964 K corresponds to eutectoid transformation from the I-phase to the C14-type Laves phase and -Zr(Ti) solid solution. The second one with an onset temperature of 1 107 K indicates the melting transformation of the eutectoid mixture.

Key words:phase transformation,quasicrystal,Ti-Zr-Ni alloy