Berkovich nanoindentation of Zr55Cu30Al10Ni5 bulk metallic glass at a constant loading rate.

• Pop-in or serrations cannot be detected at large loading rates. • Indentation hardness decreases with a constant elastic modulus under small loads. • Fracture toughness can be obtained from the total indentation energy. • Area of shear band scales with contact and residual areas. • Scaling relationships among indentation variables of Zr-based BMG were quantified. Berkovich nanoindentation experiments were conducted on Zr 55 Cu 30 Al 10 Ni 5 bulk metallic glass under a constant loading rate. Indentation hardness decreased linearly with contact depth, which defied the direct application of conventional indentation size effect model for crystalline material. Elastic modulus remained invariant under small loads, but decreased linearly under large loads. The scaling relationships between indentation variables such as contact depth, permanent depth, the maximum indentation displacement, plastic energy, the total work of indentation and their ratios were investigated. The area of shear band circle, the projected contact area at the maximum load, and the residual projected area were all found to be proportional to one another. A new methodology to determine fracture toughness was proposed based on the total work of indentation, provided that the critical indentation displacement at the onset of fracture corresponds to zero value of elastic modulus extrapolated from curve fitting. [ABSTRACT FROM AUTHOR]