Stress exponent investigation of β-Sn single crystal by depth-sensing indentation tests

Depth-Sensing Indentation tests with different loading rates were performed on β-Sn single crystal. It was found that variations in indentation load–depth curves were significantly related to loading rates. The creep penetration depths increased with increasing loading rates, although the maximum load and holding time used were the same. Higher loading rates caused larger creep deformation at the same hold time (300 s), as well as larger hardness value. Creep indentation hardness, H, defined from the concept of “work of indentation  ” varied with the volume strain occurring during the creep hold time, which is a measure of creep strain rate ε˙. Thus, strain rate sensitivity n of the indented material was determined from ln H   vs. lnε˙ curve. Our results revealed that hardness was linearly dependent on strain rate.