AFM and Nanoindentation for Surface Analysis

The combination of atomic force microscopy and nanoindentation links surface topography with local mechanical properties. This allows for the detailed characterization of heterogeneous materials down to the nanometer scale.

By combining atomic force microscopy (AFM) and nanoindentation, mechanical properties and surface structures can be directly correlated. This opens up new possibilities for the high-resolution characterization of heterogeneous materials.

Atomic force microscopy (AFM) is a well-established technique for examining surface structures on the nanometer scale. Unlike optical microscopy, the surface is not imaged using light, but rather by a nanoscale-sharp probe. This probe scans the sample line by line, enabling three-dimensional imaging of even the smallest structures. The method is particularly well-suited for applications in which surface features lie well below the resolution limit of optical systems.

When combined with nanoindentation testing, atomic force microscopy (AFM) is particularly powerful. While nanoindentation determines mechanical properties such as hardness and modulus of elasticity, AFM provides detailed information about the actual indentation geometry. This makes it possible to directly examine material protrusions, indentation effects, plastic deformations, or microcracks.

For the study, a matrix of 60 × 50 nanoindentations, each spaced one micrometer apart, was created on a polished slate sample. The maximum test force was 5 mN. The goal of the study was to determine the local hardness distribution within various mineral phases.

The subsequent AFM analysis confirms the results of the hardness mapping and provides additional information on the surface topography. Because the tip radius is typically less than 20 nm, even the smallest indentations can be reliably measured. In addition, tapping mode enables the generation of phase-contrast images.

The combination of atomic force microscopy and nanoindentation enables high-resolution characterization of surfaces and local material properties at the nanometer scale. Particularly in the case of heterogeneous materials, this combination provides new insights into the relationships between microstructure and mechanical behavior. (OM-8/26)