Calculation of elastic constants of bulk metallic glasses from indentation tests

Abstract

One of the challenges in the applications of instrumented indentation is to simultaneously measure elastic modulus and Poisson's ratio of homogeneous, isotropic materials. This work proposes empirical equations for simultaneous calculation of elastic modulus and Poisson's ratio of bulk metallic glasses (BMGs) from the ratio of the short diagonal length to the long diagonal length and the area of the Knoop imprint. The parameters presented in the empirical equations are determined first by Knoop microhardness tests of 24 BMGs, whose elastic moduli and Poisson's ratios are measured by resonant ultrasound spectroscopy. These empirical equations are further validated by the Knoop microhardness tests of other 3 BMGs, which yield elastic moduli and Poisson's ratios in good accordance with the corresponding ones available in the literature and with the results from nanoindentation tests. This work opens a new venue of Knoop microhardness test as an economical and efficient method to measure both elastic modulus and Poisson's ratio of BMGs.

Keywords

• Bulk metallic glasses
• Knoop microhardness test
• Elastic modulus
• Poisson's ratio
• Residual imprint