A Novel Tensile Device for In Situ Scanning Electron Microscope Mechanical Testing

To facilitate the study of deformation mechanisms and mechanical properties of bulk materials with feature size of centimeter level, a novel tensile device compatible with scanning electron microscope (SEM) was designed and built. Integrating the servo motor and three-stage reducer, the device could realize quasistatic loading mode with a loading speed of 10 nm/s. The device also presents broad compatibility with various types of SEMs due to its miniaturized dimensions and larger volume-output load ratio compared with existing and commercial tensile instruments. A small lead precise ball screw with left-and right-hand thread was adopted to keep the center of the specimen remain stationary without moving during the tensile testing. A novel gripping method was carefully taken into account to guarantee the alignment issues. The closed-loop control mode of the tensile process was developed. The displacement resolution of 40 nm was tested to verify the driving performance of the device. Furthermore, correction method on testing displacement was investigated based on the calibration experiments of the load sensor and displacement sensor, and the comparison tests based on stress-strain curve were carried out between the self-made device and the commercial tensile instrument (Instron 3345) to verify the feasibility and universality of the correction method.