Focused ion beam micro-dissection of cold-sprayed particles

Three different modes of cold-spray impact were compared; aluminium particles onto a piezoelectric ceramic (PZT), aluminium particles onto copper, and deep penetration of copper particles into aluminium. Adhered particles were dissected using a dual-beam scanning electron microscope/focused ion beam (SEM/FIB) for morphological and microstructural examination. It was shown that the extent of substrate deformation substantially altered the behaviour displayed during bonding of the particles. In aluminium-on-ceramic impact, no permanent deformation of the substrate was seen. Shearing of layers of metal over the ceramic left a thin coating of debris on the surface. In contrast, aluminium particles caused plastic deformation and cratering of the copper. The critical velocity for aluminium particle deposition was lower on this substrate. Copper impact onto aluminium caused adiabatic shear of the substrate, with local temperatures reaching melting point. Copper particles embedded deeply into the aluminium surface without rebounding.