High-Temperature Scanning Indentation (HTSI): using in-situ nanoindentation to quantify recovery kinetics

Thanks to recent developments in high temperature nanoindentation testing, investigation of thermally activated mechanisms at small length scales can now be carried out¹. In situ anisothermal measurements at the micron-scale of hardness, Young modulus and creep properties are now feasible. The development of the High Temperature Scanning Indentation ² technique, based on a specific high-speed loading procedure, allows quasi-continuous determination of those properties in temperature in only few hours.This technique is applied on cold-rolled pure copper and pure aluminum that undergo static recovery or/and recrystallization during thermal ramping: Hardness upon heating and cooling varies in a different manner, pointing out the occurrence of those phenomena in temperature. Part of the observed hardness drop is related to recrystallization, assessed by post-mortem EBSD microstructural characterizations.To quantify the kinetics of those phenomena, inverse analyses are run using classical restoration-based metallurgical models. The obtained parameters allow a good prediction of the hardness variations whatever the applied thermal cycle. Moreover, the impacts of the initial deformation state as well as the heating rate are clearly visible on the kinetics’ parameters. The HTSI method is an interesting tool to quantify restoration parameters as function of temperature through a few well-chosen HTSI experiments.

References:

¹Tiphéne, G.; Baral, P.; Comby-Dassonneville, S.; Guillonneau, G.; Kermouche, G.; Bergheau, J.-M.; Oliver, W. O.; Loubet, J.-L. (2021) Journal of Materials Research 36, 2383–2396. https://doi.org/10.1557/s43578-021-00107-7.

²Comby-Dassonneville, S.; Tiphéne, G.; Borroto, A.; Guillonneau, G.; Roiban, L.; Kermouche, G.; Pierson, J.-F.; Loubet, J.-L.; Steyer, P. (2021) Applied Materials Today, 24, 101126. https://doi.org/10.1016/j.apmt.2021.101126.