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

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 investigate d. It is shown that the flow/fracture stress was independent of superimpose d hydrostatic pressure over the range 50-575 MPa, suggesting that the flow behavior follows the von Mises criterion. However, the macroscopic orientat ion of the fracture plane relative to the stress axis was strongly affected by changes in stress state, suggesting some normal stress dependence to th e flow/fracture behavior. The fracture behavior was also studied on both no tched and precracked bend bars for both plate thicknesses. The average frac ture toughness obtained from seven fatigue precracked specimens taken for b oth plate thicknesses was 17.9 +/- 1.8 MPa root m, while the notched toughn ess obtained on specimens with notch root radii ranging from 65 to 250 mu m taken from both plate thicknesses were in the range of 91-131 MPa root m. (C) 2000 Elsevier Science Ltd. All rights reserved.