Nowadays, instrumented indentation is routinely used in quality control as well as in many different areas of industrial and academic research. This technique is generally known as nanoindentation because the indentation depths are often much smaller than in traditional Vickers or Rockwell hardness measurements. In addition, the instrumented indentation method measures elastic modulus and hardness of a wide range of materials by applying load and determining the indentation depth.
Due to automated measurement including the analysis, a wide range of measurements can be carried out and examined automatically without any operator intervention. Thanks to the versatility of the Anton Paar nanoindentation systems and their related software, a variety of loading profiles can now be applied on specific materials to expose the unique material characteristics.
For instance, materials with surface coatings or with graded properties can be analyzed with cyclic loading to determine their gradient of hardness; polymers and other materials with time-dependent properties can be indented with various indentation rates or in constant strain rate mode in order to achieve their dynamic response. To observe the slip phenomena, certain indentation-related experiments such as micro pillar compression can be advantageously carried out in displacement control mode.
This article summarizes the variety of methods included in the Anton Paar Indentation software. All methods are comprehensively described and application examples are provided. The aim of this article is to guide nanoindenter users in their selection of the most appropriate indentation process.
The most common type of indentation is standard indentation that allows simple and efficient measurements of hardness and elastic modulus. This method is defined in the ISO 14577 standard. The maximum indentation load and the duration of the hold period have to be specified by the user. Figure 1a shows the load profile and Figure 1b shows the resulting load-displacement curve.
Figure 1. a) Standard indentation load profile, b) resulting load-displacement indentation curve.
Advanced Indentation Modes for Single Load Indentations
The advanced measurement mode is a technique of instrumented indentation that allows performing one single indentation measurement where the user independently defines the loading and the unloading rates. Due to this mode, different loading types can be selected making it possible to either speed up the total test time or to examine the response of different types of materials to different loading rates. The advanced measurement mode can be employed for most regular indentation testing applications.
Instrumented indentation (nanoindentation) testers from Anton Paar provide three key types of indentation loading:
- Constant Strain Rate
- Quadratic Loading
- Linear Loading
Test procedures based on Linear or a Constant Strain Rate type of loading can be either force-controller or displacement controlled.
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This information has been sourced, reviewed and adapted from materials provided by Anton Paar GmbH.
For more information on this source, please visit Anton Paar GmbH.