Depth-sensing indentation for assessing the mechanical properties ofcold-sprayed Ta

The stress–strain behaviour of cold-sprayed Ta coatings, deposited onto Al and steel substrates, was studiedby depth-sensing spherical and sharp (Berkovich) indentation testing, and was compared to that of anannealed Ta sheet. The mechanical properties of the coatings, free of any scale-dependence, are insensitive tothe presence of a lamellar structure, indicating strong, tight bonding between cold-sprayed Ta particles.Accordingly, the coatings are isotropic. The stress–strain curves reveal that the coating material experiencedsome degree of work-hardening during cold-spraying; indeed, the sprayed particles were plasticallydeformed at impact. This was confirmed by line profile analysis on XRD patterns. The consistency between theresults from different indentation testing techniques provides a means to cross-validate the entire analysis.