Ti and Zr Intermixing of quasicrystals in Ti-based Alloys

Abstract

More than 500 quasicrystals have been reported since the first discovery of quasicrystals in an Al-Mn alloy in 1984. Quasicrystals are known to exhibit striking feature of five-fold rotational symmetry, which is forbidden in crystalline materials. Their sharp diffraction peaks in X-ray and transmission electron microscopy, however, also make them to have different structural properties from that of amorphous materials. It is known that Ti-based quasicrystals, constituting the second largest group, are known relatively easy to obtain and are showing a strong possibility for the hydrogen storage applications. Because of these advantages, we studied Ti-Zr-Ni alloys with fixing the Ni concentration at 17 at. %, while Ti and Zr compositions were varied from 33 to 50 at. % and investigated the structural development from the liquids to solids. The samples were arc-melted in an Ar atmosphere and subsequently quenched on the 2mm thick stainless steel wheel which rotates at a different quenching rate. No significant structural difference was noticed when Ti concentration was varied approximately 20 at. % from the Ti45Zr38Ni17 alloys. Our combined results suggest that Ti-Zr-Ni quasicrystals are relatively stable to form.