Formation of Icosahedral Quasicrystalline Phase in Zr₇₀TM₁₀Pd₂₀ (TM = Fe, Co, or Cu) Ternary Glassy Alloys

Abstract

A nanoscale icosahedral quasicrystalline phase was confirmed as a primary precipitation phase in the melt-spun Zr₇₀TM₁₀Pd₂₀ (TM = Fe, Co, or Cu) ternary glassy alloys with a two-stage crystallization process. The onset temperature of the transformation from amorphous to icosahedral phase is 713 K for Fe-, 696 K for Co-, and 680 K for Cu-containing alloys at the heating rate of 0.67 Ks⁻¹. The size of the icosahedral particles is in the range of 20 to 50 nm for the Zr₇₀Cu₁₀Pd₂₀ glassy alloy annealed for 120 s at 720 K. The icosahedral phase has a very fine particle size in a diameter range below 10 nm for the Zr₇₀Fe₁₀Pd₂₀ and Zr₇₀Co₁₀Pd₂₀ alloys. The crystallization reaction after the first exothermic peak results in the transition from the icosahedral to crystalline phases through a sharp exothermic reaction. Thus, the formation of the nanoscale icosahedral phase indicates the possibility that an icosahedral short-range order exists in the present glassy alloys.