Instrumented indentation of a Pd-based bulk metallic glass: Constant loading-rate test vs constant strain-rate test

Abstract

Most of the previous nanoindentation experiments on bulk metallic glasses (BMGs) were made under a constant 'loading rate,' although 'strain rate' is a more useful parameter than loading rate to analyze the inhomogeneous plasticity in the BMG according to the classic free-volume theory. Here, we explore the strain-rate dependency of plastic characteristics in a Pd-based BMG through nanoindentation tests under a variety of constant strain rates(0.01-0.25 s(-1)). The results are compared with those from nanoindentations under various constant loading rates (0.05-5 mN/s) and discussed in terms of the influences of strain rate on the plastic flow characteristics in the BMG.