Roles of in-situ forming hard particles in a Zr-based bulk-metallic glass during monotonic and cyclic loading

Zr₆₇Ni₂₀Cu₅Al₈ (in at. pct) is a bulk-metallic glass (BMG) with in-situ forming hard particles. Some crystalline particles can be observed in the polished beam samples under optical microscopy (OM). The hardness measurements show that these crystalline particles are harder than the matrix of Zr₆₇Ni₂₀Cu ₅Al₈. The energy-dispersive spectroscopy (EDS) analyses demonstrate that there is little difference in the compositions between the crystalline particles and the matrix. The Zr₆₇Ni₂₀Cu ₅Al₈ BMG under compressive loading exhibits yield strength of 1580 MPa with an up to 7.7 pct fracture strain. The fatigue behavior of Zr₆₇Ni₂₀Cu₅Al₈is investigated under four-point-bending loading. The fatigue results show that the fatigue limit of Zr₆₇Ni₂₀Cu₅Al₈ is approximately 361 MPa, based on the stress range. It is generally found that the fatigue cracks initiate from the hard particles. The influence of the hard inclusions on the fracture and fatigue behavior of Zr-based BMGs is discussed.