Thermal contact-induced displacement drift in high-temperature nanoindentation

Based on the analysis of heat transfer between indenter at room temperature and hot sample during their contact, this paper mainly studies the influence of thermal contact-induced expansion of the indenter holder on the displacement measurement in high-temperature instrumented nanoindentation. First of all, we derive an analytical solution of temperature distribution of the holder from the basic theory of heat conduction by appropriately simplifying the analysis model of hot nanoindentation, and use it to study the additional displacement caused by thermal expansion. Secondly, a finite element model (FEM) is established to investigate the thermal expansion-induced drift in hot nanoindentation to verify the analytical solution. It is found that the contact thermal properties between indenter and hot sample may significantly affect the distribution of temperature in holder. The thermal contact conductance between indenter and test sample varies from material to material, which can lead to the difference of several orders of magnitude of holder's thermal expansion. The research results may help to optimize the test program and improve the reliability of high-temperature instrumented nanoindentation.