Glass formation and crystallization in binary Zr–Pt systems

Abstract

Previous rapid solidification studies of Zr–Pt alloys have focused primarily on compositions very close to the Zr₈₀Pt₂₀ eutectic. In the current work, a wide range of alloys, Zr _x Pt_{100 − x} (69 ≤ x ≤ 81), were synthesized by melt spinning to examine their starting structures and devitrification behaviours. Similar to the frequently reported formation of a metastable quasicrystalline phase during heating of near-eutectic compositions, ribbons with Zr contents as low as 75 at.% show comparable transformations, but at higher temperatures, before transforming to the stable Zr₅Pt₃ structure. With the quench rate used in this study, a further decrease below 75 at.% Zr precludes the formation of the metastable quasicrystalline phase and instead results in crystallization directly to the stable Zr₅Pt₃ structure. Preliminary analysis of the transformation kinetics reveals a lower activation energy for the transformation of an amorphous Zr–Pt structure to the metastable quasicrystal phase in comparison to the stable Zr₅Pt₃ phase.

Acknowledgements

This work was supported by the US Department of Energy, Basic Energy Sciences, through Iowa State University under Contract No. W-7405-ENG-82.