Micro-scale strength evaluation for bonding interface of cold sprayed coatings

A micro-scale interface strength evaluation technique is essential for evaluating cold-sprayed materials. A focused ion beam (FIB) micro strength test enables the micro-scale evaluation of the interface mechanical properties. However, this technique cannot be used to measure the strain in a specimen. This work discusses the possibility of strain measurement by combining this technique with image analysis in a newly designed test setup. Moreover, the micro stress-strain curve for cold-sprayed copper was obtained. This improved method enables us to measure stress with a precision of 5 MPa and strain with a precision of 0.015. It was determined that some local regions can deform plastically, which could not be determined with conventional micro- and macro-scale evaluation methods. These results proved that the coating is non-uniform, while also revealing various microstructure and mechanical properties.