Spherical Nanomechanical Characterization of Novel Nanocrystalline Cu Cold Spray Manufactured Materials*

The novel mechanical, microstructural, and functional properties associated with nanocrystalline metal materials has brought about interdisciplinary interest and curiosity. Nanostructured metals can be manufactured by way of multiple methods; however, during the course of this research the method studied herein is employs severe plastic deformation processing via cold spray powder deposition. TEM and SEM analysis confirmed the noteworthy grain refinement brought about by cold spray for two copper feed stocks. More specifically, the two types of copper powders were that of conventional gas atomized Cu as well as nanostructured Cu powders produced by way of spray drying and agglomeration. As such, the classical nanoindentation properties of hardness and Elastic modulus are experimentally determined using both static and dynamic nanomechanical testing. Dynamic spherical nanoindentation methodologies are employed to unveil the cold spray consolidated coating’s stress-strain response and flow behavior. The mechanical flow curves extracted herein suggest that the protocol refinements proposed by Leitner, Maier-Kiener, and Kiener may have fundamentally advanced spherical nanoindentation testing at large.