High-Throughput High-Resolution Digital Image Correlation Measurements by Multi-Beam SEM Imaging.

Background: Recent improvements in spatial resolution and measurement sensitivity for high-resolution digital image correlation (HR-DIC) now provide an avenue for the quantitative measurement of deformation events and capturing the physical nature of deformation mechanisms. However, HR-DIC measurements require significant time due to scanning electron image acquisition; such a limitation prevents the widespread use of HR-DIC for material characterization. Objective: Apply a novel SEM acquisition technology to enhance HR-DIC measurements for high throughput applications. Methods: Multi-beam SEM technology is employed to image an entire gauge length at once at high resolution and at nearly a hundredfold acceleration of typical HR-DIC image acquisition, even when automated stage movement and image acquisition are employed. These images were fed into a discontinuity-tolerant HR-DIC software to determine slip localization induced by non-metallic inclusions and grain structure. Results: Slip localization was able to be analyzed to an unprecedented level, with over 210,000 slip bands able to be investigated, with the most intense slip localizing near and parallel to twin boundaries and in the vicinity of non-metallic inclusion clusters. Additionally, secondary slip activation and grain boundary shearing by intense dislocation pileups are observed to reduce slip amplitude near and parallel to twin boundaries. Conclusions: By performing HR-DIC in conjunction with a multi-beam SEM, high-throughput measurements of large field-of-view, high-resolution images were able to be performed in a timely manner. These measurements provided an immense number of slip events for statistical analysis to be performed on to relate to microstructural features. [ABSTRACT FROM AUTHOR]