The effects of annealing on fatigue behavior in Zr-based bulk metallic glasses

The effects of annealing and fatigue on the local structure of Zr ₅₀&Cu ₄₀Al ₁₀ and Zr ₆₀Cu ₃₀Al ₁₀ bulk metallic glasses (BMG) were investigated using the pair density function (PDF) analysis of synchrotron X-ray and neutron diffraction data. Our results indicate that the two compositions respond differently to annealing. The first PDF peak becomes sharper after annealing in Zr ₅₀Cu ₄₀Al ₁₀ with its intensity increasing, indicating that short-range ordering may be induced after the heat treatment. On the other hand, in Zr ₁₀Cu ₃₀Al ₁₀, the effects due to the heat treatment on the local structure are more subtle. Separately, the as-quenched and annealed alloys with the composition Zr ₅₀Cu ₄₀Al ₁₀ were subjected to fatigue loading conditions with ∼ 10 ⁶ compression cycles. The room temperature measurements showed changes in the local structure with fatigue especially for the annealed sample, involving the Cu-Zr correlations. Our results suggest that the physical properties of BMGs upon fatigue loading conditions may become accentuated due to the structural relaxation brought upon by annealing, leading to observable structural changes at the atomic level from fatigue.