Four-point-bending-fatigue behavior of the Cu45Zr45Ag7Al3 bulk metallic glass

•Four-point-bend fatigue experiments were conducted on the Cu45Zr45Ag7Al3 BMG.•The fracture surface can be divided into four regions.•Fatigue fracture behavior of this glassy alloy is due to the free volume increase.

Four-point-bend fatigue experiments were conducted on Cu45Zr45Ag7Al3 bulk metallic glass, which was done by the use of an electrohydraulic machine, at a frequency of 10 Hz (using a sinusoidal waveform) with an R ratio of 0.1, where R = σmin / σmax (σmin and σmax are the applied minimum and maximum stresses, respectively). This material shows a fatigue-endurance limit and fatigue ratio of 386 ± 5 MPa and 0.26 ± 0.01, respectively, and the fracture toughness is estimated to be about 23–30 MPa·m1/2. The fatigue-fracture morphology indicated that Cu45Zr45Ag7Al3 has a significantly brittle fracture mode. The fracture surface can be divided into four regions: crack initiation, crack propagation, fast fracture, and melting regions. The fracture mechanism is discussed.