Hardness variation with indenter sharpness in an Au thin-film

Area of Science:

• Materials Science
• Nanotechnology
• Mechanical Engineering

Background:

• Nanoindentation is a key technique for measuring mechanical properties of thin films.
• Indenter geometry, particularly its sharpness, can influence measured hardness values.
• Variations in indenter shape due to usage can introduce errors in nanoindentation testing.

Purpose of the Study:

• To investigate the effect of indenter shape on hardness measurements in thin-film nanoindentation.
• To develop and validate a method for correcting nanoindentation data based on indenter sharpness.
• To determine the intrinsic hardness of a gold thin film independent of indenter geometry.

Main Methods:

• Preparation and morphological characterization of two Berkovich indenters with different sharpness using atomic force microscopy.
• Performing nanoindentation tests on a 1.2 micrometer-thick gold thin film using both indenters.
• Analyzing nanoindentation load-displacement data and applying an indenter sharpness correction parameter.

Main Results:

• Blunter indenters resulted in higher peak indentation loads at equivalent depths compared to sharper indenters.
• Correction using the indenter sharpness parameter led to overlapping load-displacement curves.
• Consistent hardness values were obtained regardless of indenter sharpness, with only a 0.6% difference.

Conclusions:

• Indenter sharpness is a critical factor that must be accounted for in nanoindentation, especially at shallow depths.
• The developed correction method effectively normalizes data, yielding reliable intrinsic hardness values.
• Accurate material property characterization requires careful consideration and correction of indenter geometry effects.