Preparation method for in situ tensile testing in transmission electron microscopy based on push-to-pull chip

In the research and development of advanced metallic materials at the micro- and nano-scale, in-situ mechanical characterization plays a critical role in evaluating material mechanical behavior. The Bruker Push-to-Pull (PTP) chip-based in-situ mechanical testing technique offers broad experimental flexibility, enabling an extended range of mechanical responses in such studies. However, owing to its ultrahigh displacement resolution-on the order of several nanometers-the welding process between the sample and the chip must meet extremely stringent requirements. To address this, preliminary work including fabrication of contacts on sample slice and deposition of platinum pads on PTP were completed by focus ion beam. A large ion beam current was selected to bombard and co-mingle contacts and pads together. Results demonstrate that this method not only achieves robust bonding between the specimen and the PTP chip, but also ensures that the load transfer from the actuator to the PTP structure maintains a well-controlled uniaxial tensile condition throughout the process. The combination of pads and contacts also provide a sufficient thinning angle for thinning to satisfy the stringent thickness requirements of transmission electron microscopy (TEM) observation. The present work provides a precise, efficient, and controllable preparation strategy for in situ mechanical testing at the micro/nano scale.