PROPERTIES OF QUASI-CRYSTALS IN THE TI-ZR-NI SYSTEM

The amorphous-icosahedral phase transformation in Ti20Zr60Ni20 alloy i s investigated by differential scanning calorimetry, X-ray structural, resistometric, and dilatometric analysis, and microhardness measureme nt. The transformation is polymorphic and occurs by a nucleation and g rowth mechanism. The electrical resistance and temperature coefficient of linear expansion of the icosahedral phase are close to those for t he amorphous phase, whereas the microhardness and temperature dependen ce of the specific heat are close to those for crystalline phases. The thermal and transport properties of metastable quasi-crystals in the Ti-Zr-Ni system are close to the properties of metallic glasses in thi s system. The electronic transport properties of the icosahedral phase in the Ti-Zr-Ni system are evidently associated with its compositiona l disordering.