Measurement of hardness and elastic modulus by load and depth sensing indentation: Improvements to the technique based on continuous stiffness measurement

The method to measure hardness and elastic modulus of small volumes of material by instrumented indentation was developed in the early works of Oliver and Pharr (1992, 2004). This helped to establish the field of small scale nanomechanical testing. Since then, several advances in measurement electronics have enabled testing over a wider range of test conditions (speeds) using methodologies that were developed earlier. Here, we present an updated overview of the various factors that affect the precision and accuracy of the nanoindentation test results at different test conditions with specific focus on the continuous stiffness measurement technique (CSM). A step-by-step procedure for performing a CSM based indentation test is presented. In addition, calibration procedures that yield the best possible precision and accuracy at the chosen test conditions are also presented. Finally, we present an assessment and comparison of the different testing procedures.

Automated summary

The method for measuring hardness and elastic modulus of small volumes of material through instrumented indentation was initially developed by Oliver and Pharr in their early works. This has led to advancements in the field of small scale nanomechanical testing, with improvements in measurement electronics allowing testing under a wider range of conditions. The article provides an updated overview of factors affecting precision and accuracy of nanoindentation test results, focusing on the continuous stiffness measurement technique (CSM) and presenting a step-by-step procedure for conducting CSM based tests, along with calibration procedures for optimal precision and accuracy. Additionally, an assessment and comparison of different testing procedures is presented.