Measurement of fracture toughness of copper via constant-load microscratch with a spherical indenter.

Fracture toughness can be measured by microscratch test from objective force and depth measurement, which is much convenient than indentation approach and conventional means, since initial notch or pre-crack is not required. Micro-scratch test was conducted on copper under a spherical probe of radius 105 μm and constant applied normal load with the aim of characterizing fracture toughness of copper by sliding technique with a sphere. Scratch variables such as normal load, lateral load, friction coefficient, and penetration depth were analyzed, and different methodologies for calculating fracture toughness were compared. Linear elastic fracture mechanics was found to be inapplicable to scratch of elastic-plastic material with sufficient plasticity under a spherical probe, while energetic size effect law can be successfully applied to characterize fracture toughness by microscratch test with a sphere abrading metallic material. • Fracture toughness of copper was obtained from scratch test with a spherical indenter. • Correlations among scratch variables for a sphere sliding on copper were examined. • Spherical indentation and scratch test with a spherical indenter were compared. • Different methodologies for computing fracture toughness by scratch test were compared. • The energize size effect law is applicable to characterize fracture toughness of metallic material by scratch test. [ABSTRACT FROM AUTHOR]