Redistribution of alloying elements in quasicrystallized ${\mathrm{Zr}}_{65}{\mathrm{Al}}_{7.5}{\mathrm{Ni}}_{10}{\mathrm{Cu}}_{7.5}{\mathrm{Ag}}_{10}$ bulk metallic glass

We report experimental evidence on redistributions of alloying elements in a partially quasicrystallized ${\mathrm{Zr}}_{65}{\mathrm{Al}}_{7.5}{\mathrm{Ni}}_{10}{\mathrm{Cu}}_{7.5}{\mathrm{Ag}}_{10}$ bulk metallic glass. Energy-filtered elemental maps show that the partitioning of silver, zirconium, and aluminum occurs in the quasicrystallized glass. Silver is found to enrich into quasicrystals, but zirconium and aluminum are slightly depleted from the quasicrystals. These observations suggest that the amorphous-to-quasicrystal transformation in this alloy is not a simple polymorphous reaction and a long-range diffusion is involved in the devitrification, probably prior to the quasicrystallization.

Figure 1

Energy-filtered HREM image of an as-prepared ${\mathrm{Zr}}_{65}{\mathrm{Al}}_{7.5}{\mathrm{Ni}}_{10}{\mathrm{Cu}}_{7.5}{\mathrm{Ag}}_{10}$ bulk metallic glass.

Figure 2

(a) Bright field images of the ${\mathrm{Zr}}_{65}{\mathrm{Al}}_{7.5}{\mathrm{Ni}}_{10}{\mathrm{Cu}}_{7.5}{\mathrm{Ag}}_{10}$ metallic glass annealed at $700\mathrm{K}$ for $4\min$, and (b) a nanoparticle and corresponding nanobeam electron diffraction pattern. This particle was selected for EF-TEM characterization in Fig. 3.

Figure 3

(Color) EF-TEM characterization of the elemental distributions in the quasicrystallized metallic glass. The succeeding images show jump-ratio maps recorded with $20\text{−}\mathrm{eV}$ windows on either side of (a) $\mathrm{Zr}\text{−}{M}_{45}$, (b) $\mathrm{Ag}\text{−}{M}_{45}$, (c) $\mathrm{Al}\text{−}{L}_{23}$, (d) $\mathrm{O}\text{−}K$, (e) $\mathrm{Cu}\text{−}{L}_{23}$, and (f) $\mathrm{Ni}\text{−}{L}_{23}$. The accompanying profiles highlight the composition difference between the nanoparticle and the glassy matrix.