Quantitative Hardness Measurement by Instrumented AFM-indentation.

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Understanding nanoscale mechanical properties is crucial for designing advanced materials.
• Atomic-level plasticity events govern macroscopic material behavior.
• Accurate hardness measurements require precise force-distance characterization.

Purpose of the Study:

• To develop and apply a method for instrumented hardness measurements with atomistic resolution.
• To investigate single plasticity events on an Au(111) surface.
• To correlate nanoscale deformation with macroscopic hardness.

Main Methods:

• Utilizing amplitude-modulated non-contact atomic force microscopy (AFM) and atomic force spectroscopy.
• Implementing a rigorous experimental procedure for force sensor and deflection detection calibration.
• Developing a data analysis method to extract force-penetration curves from force-distance data.

Main Results:

• Observed clear elastic deformation followed by discrete plasticity events (pop-ins) of 1-2 Burger's vectors.
• Quantified the work of plasticity from the measured indentation curves.
• Determined hardness by combining indentation data with AFM imaging of residual indents.

Conclusions:

• The applied AFM technique enables atomistic resolution of plasticity events during hardness testing.
• Plasticity events at the nanoscale occur in discrete, quantized steps.
• This method provides a pathway for precise nanoscale hardness characterization.