High temperature nanoindentation is a popular method with many applications in materials science, bioscience, coatings, and additive manufacturing. The method is generally used for studying the mechanical properties of materials at small length scales.

Since the mechanical properties are generally temperature dependent, the development of high temperature nanoindentation will have a significant impact compared to industrial applications where materials are used or processed at high temperature.

The development of nanoindentation

Indentation tests cover a range of techniques to identify the mechanical properties of materials.

These tend to follow the same format: indent a test material with a probe until an indentation is created, and characterize the mechanical properties of that material as a function of load size, displacement indenter and sample, as well as cavity geometry.

While large-scale indentation methods (such as Vickers or Rockwell hardness testing) can offer a convenient measurement of the relative hardness of various materials, precision measurements can only be achieved using small loads and indentations.1 Nanoindentation brings this technique to its logical conclusion.

Nanoindentation is identified by charges ranging from a few micronewtons to a few millinewtons distributed over an area ranging from a few square nanometers to a few square micrometers.

Nanoindentation produces deformations on the surface of the material that are so tiny that they usually cannot be resolved using light microscopy.

Nano-indentation offers a number of advantages over macro-indentation. Indentations at this scale facilitate the ability to measure the mechanical properties of films, coatings and small samples without influence from the underlying substrate.2

In addition, nanoindentation can be used to study micro-scale characteristics or variations in material properties, such as the different phases that make up complex microstructures.3

The first nanoindentation systems were first developed in the 1970s, driven by an increased interest in microelectronics and biomaterials, which involved the study of small volume samples and thin films.4

Nanoindentation is now widely used for material characterization, mainly due to the fact that many systems now have the ability to automate analysis and therefore only require a clean, flat (and relatively small) sample to work.5

As the techniques were developed in the early 1990s (including Oliver and Pharr’s analysis), measurements can be obtained directly from a force-extension curve without the need to characterize the footprint. herself.6

A traditional nanoindentation procedure can automatically produce statistically evaluated measurements of a wide range of mechanical properties, including hardness and modulus of elasticity.

High temperature nanoindentation

As with most mechanical properties, measurements of hardness and modulus of elasticity acquired by nanoindentation are based on temperature dependent characteristics.

In order to accurately represent the mechanical behavior of engineered materials with high operating or processing temperatures, high temperature nanoindentation must be performed.

High temperature nanoindentation involves controlled heating of sample and indenter to extreme temperatures – temperatures around 800°C are generally used. High temperature nanoindentation is often performed under vacuum to avoid sample oxidation and other atmospheric effects.

High-temperature nanoindentation exhibits numerous technical challenges, such as sample oxidation, temperature drift and heat management.

However, the advancement of high-temperature nanoindentation systems suchlike the Alemnis High-Temperature Module (HTM), has facilitated a prevailing use of high-temperature nanoindentation.

Thus, the popularity of high-temperature nanoindentation continues to grow, and it is now a conventional method of probing temperature effects on material properties.

Applications of High-Temperature Nanoindentation

High-temperature nanoindentation offers a new approach for fundamental materials research. The exceedingly localized nature of high-temperature nanoindentation implies that it can be utilized for comprehensive investigations of the kinetic features of a material’s behavior.

High-temperature nanoindentation has been used effectively and with success to characterize a wide range of temperature-induced material effects.

These include phase transitions in semiconductors like Si and Ge7, the crystallization performance of bulk metallic glasses8, stress-strain of P91 steel9 and the origins of atomic-level plasticity in solids.10,11

High-temperature nanoindentation is also well-suited for use in combination with several imaging techniques (including SEM and TEM) or measurements of electrical measurements to general a common understanding of the behavior of materials at the nanoscale.12

In the latest developments, these composite in-situ techniques facilitate real-time investigation of temperature effects on microstructure and the interactions between mechanical, thermal and electrical effects at the nanoscale.

Impact testing and multicycle indentation are also being utilized to study the resistance a material demonstrates towards deformation at various temperatures.

Load-displacement curves obtained between room temperature and 500 °C for impact tests on a CrN coating with 10k impacts. Shown is an overlay of curves from the 20th to the 40th impact and residual imprints from room temperature and 500 °C nano-impact tests (1k and 100k) using a diamond flat punch.

Load-displacement curves obtained between room temperature and 500°C for impact tests on a CrN coating with 10k impacts. Shown is an overlay of curves from the 20th to the 40th impact and residual imprints from room temperature and 500°C nano-impact tests (1k and 100k) using a diamond flat punch. Image Credit: Alemnis AG

High-temperature nanoindentation systems are well adapted to rapid thermal cycling because nanoindentation testing utilizes small-sample volumes. The investigation of thermo-mechanical fatigue of thin films that are of significant interest in the electronics and semiconductor industries exploits such characteristics.5

As well as facilitating compressive testing, high-temperature nanoindentation systems developed by Alemnis also enable tensile testing. This allows for the high-temperature dynamic testing of microscale samples and features, such as those yielded by focused ion beam or lithography.

Alemnis High-Temperature Nanoindentation Systems

The Alemnis Standard Assembly (ASA) is the most dynamic indentation system in the world, offering a modular platform for developing nanomechanical testing methods that are application-specific.

Modifying the ASA with one of four high temperature modules produces a strong, high-performance and economical system for high temperature nanoindentation applications.

Alemnis high-temperature modules facilitate heating up to 200°C in air and up to 1000°C in vacuum. The system contains three thermal sensors with < 1°C resolution and two independent temperature control loops for precision temperature setting and regulation.

The result is a high-temperature nanoindentation environment that can be controlled with great accuracy while maintaining a short temperature stabilization time.

Contact Alemnis today to find out more about ASA’s capacity for high temperature nanoindentation applications.

The references

  1. Fischer Cripps, AC Introduction to contact mechanics. (Springer Science & Business Media, 2000).
  2. Fischer-Cripps, AC A review of analytical methods for submicron indentation testing. Empty 58, 569-585 (2000).
  3. Fischer Cripps, AC The IBIS nanoindentation manual. (Fischer-Cripps Laboratories, 2009).
  4. Poon, B., Rittel, D. & Ravichandran, G. An analysis of nanoindentation in linearly elastic solids. International Journal of Solids and Structures 45, 6018-6033 (2008).
  5. Wheeler, JM, Armstrong, DEJ, Heinz, W. & Schwaiger, R. High temperature nanoindentation: state of the art and future challenges. Current opinion in solid and materials science 19, 354-366 (2015).
  6. Oliver, WC & Pharr, GM An improved technique for determining hardness and modulus of elasticity using load and displacement sensing indentation experiments. Materials Research Journal 7, 1564-1583 (1992).
  7. Chavoshi, SZ & Xu, S. Temperature-dependent nanoindentation response of materials. 14.
  8. Nieh, T., Iwamoto, C., Ikuhara, Y., Lee, K. & Chung, Y. Comparative studies of the crystallization of an amorphous bulk Zr-Al-Ti-Cu-Ni alloy. Intermetallic 12, 1183-1189 (2004).
  9. A. Ruiz Moreno, P. Hähner, F. Fumagallia, V. Haiblikova, M. Conte, N. Randall, Stress-strain curves and mechanical parameters derived from P91 steel from spherical nanoindentation at a temperature range , Materials and design, 194, (2020) 108950
  10. Quantitative overview of dislocation nucleation from high temperature nanoindentation experiments | Natural materials. https://www.nature.com/articles/nmat1429.
  11. Choi, I.-C., Brandl, C. & Schwaiger, R. Thermally activated dislocation plasticity in body-centered cubic chromium studied by high temperature nanoindentation. Acta Materialia 140, 107-115 (2017).
  12. Nili, H., Kalantar-zadeh, K., Bhaskaran, M. & Sriram, S. Nanoindentation in situ: Exploring multifunctionality at the nanoscale. Advances in Materials Science 58, 1–29 (2013).

This information has been obtained, reviewed and adapted from documents provided by Alemnis AG.

For more information on this source, please visit Alemnis AG.

About The Author

Related Posts

Leave a Reply

Your email address will not be published.