Deformation and fracture toughness of a bulk amorphous Zr–Ti–Ni–Cu–Be alloy

Abstract

The flow behavior and fracture toughness of two different plate thicknesses (i.e. 4 and 7 mm) of a bulk amorphous Zr–Ti–Ni–Cu–Be alloy was investigated. It is shown that the flow/fracture stress was independent of superimposed hydrostatic pressure over the range 50–575 MPa, suggesting that the flow behavior follows the von Mises criterion. However, the macroscopic orientation of the fracture plane relative to the stress axis was strongly affected by changes in stress state, suggesting some normal stress dependence to the flow/fracture behavior. The fracture behavior was also studied on both notched and precracked bend bars for both plate thicknesses. The average fracture toughness obtained from seven fatigue precracked specimens taken for both plate thicknesses was 17.9±1.8 MPa√m, while the notched toughness obtained on specimens with notch root radii ranging from 65 to 250 μm taken from both plate thicknesses were in the range of 9l–131 MPa√m.