A Nanoindentation Instrument for Characterizing Mechanical Properties of Materials Under High-Frequency Vibration

The nanoindentation technique is one of the main techniques for characterizing the mechanical properties of materials at micro and nano scales, which has been extensively employed in recent years. Currently, most nanoindentation instruments adopt the quasistatic testing method. However, when components and devices work under actual conditions, most of them serve in the state of high-frequency vibration (HFV). In this study, to investigate the response of materials operating in the state of HFV to nanoindentation, a HFV nanoindentation instrument consisting of a traditional nanoindentation device and a vibration device was developed. The nanoindentation device performed the indentation process, and the vibration device provided a stable HFV. By performing the quasistatic indentation test and vibration indentation tests at different vibration amplitudes on Ti6Al4V, the effects of HFV on the load-depth curves, the microscopic characteristics of the residual indentation, and hardness values were investigated. The results showed that when increasing the vibration amplitude from 0 to 3~\mu \text{m} , the hardness measured by the HFV nanoindentation instrument decreased from 3.5 to 0.8 GPa, and correspondingly, the area and depth of the residual indentation increased. Besides, compared to quasistatic conditions, shear bands were prone to appear around the residual indentation at a relatively small load for nanoindentation testing under HFV conditions, which could be attributed to continuous indentation shock. This study develops a HFV nanoindentation instrument, which is of great scientific significance and application value for the evaluation of service performance and deformation mechanisms of materials serving in HFV conditions.