Spall failure of additively manufactured two-layered Cu–Ni bimetallic alloys

The dynamic tensile spall failure of additively manufactured (AM) two-layered bimetallic GRCop-84—Inconel® 625 alloys, with planar and slanted interfaces, is investigated using uniaxial-strain plate-impact gas-gun experiments. Multiple photon Doppler velocimetry (PDV) is used to monitor the back (free) surface velocity profiles and to determine the influence of the interface geometry on the spall failure. Micrographs of cross sections of recovered impacted samples reveal failure along the interface as well as in-material regions. Spall strengths determined from pull-back signals captured with the use of the multiple PDV probes illustrate different location-specific values for the same sample, corresponding to failure occurring in Inconel® 625, or GRCop-84, or along their interface, depending on the geometry of the interface. The results obtained from the experiments employing multiple PDV probes correlated with microstructural observations of cross sections of recovered impacted samples, provide a useful method for determining the complex spall failure response of two-layered bimetallic alloys, including the differentiation of the response of the respective alloy materials relative to that of the interface, in the same experiment.