Modulus and hardness determination using instrumented nanoindentation tests – How reliable are the results?
September 29-October 4, 2019
Nanoindentation testing has developed to be a “standard” test method to analyze mechanical properties on a sub-micrometer length scale with a high degree of control, dealing with tiny forces and displacements.
This method was initially established in academic research. It is still under remarkable development due to competing manufacturers in cooperation with research groups.
On the other hand this technique has become an established test method for industrial material analysis making use of the high degree of automatization and standardization.
When data analysis is a “black box” for occasional user, high efforts are required of the manufacturer to ensure that reliable data are obtained.
In order to answer the question about reliability, we will cover error sources to the modulus and hardness values calculated by the nanoindenter software.
Potential error sources range from inadequate sample preparation/mounting, unsuitable parameter selection, discrepancies between model assumption and sample deformation geometries to faulty instrument calibration. Improper tip area calibration is the most common instrument calibration issue. Also the basic calibrations (force, travel, …) need to be as precise as possible, since all mechanical sample properties are derived from them.
There has been a lot of debate about resolution and data acquisition speed. Here we want to set a focus on the accuracy of nanoindentation test data.
Dennis Bedorf, Martin Knieps, Wolfgang Stein, and Daniel Habor, "Modulus and hardness determination using instrumented nanoindentation tests – How reliable are the results?" in "Nanomechanical Testing in Materials Research and Development VII", Jon Molina-Aldareguia, IMDEA-Materials Institute, Spain Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/nanochemtest_vii/22