Single Impact Bonding of Cold Sprayed Ti-6Al-4V Powders on Different Substrates

The objective of this study is to investigate particle deformation and bonding over a wide range of impact conditions, cold spraying of spherical Ti-6Al-4V powders was carried out with nitrogen as process gas onto titanium grade II, Ti-6Al-4V, and aluminum and magnesium alloy substrates. The bond strength was assessed by applying a modified cavitation test. The corresponding impact morphologies and fracture morphologies, as obtained after cavitation testing, were studied by scanning electron microscopy. The investigations demonstrate that bonding and adhesion of spherical Ti-6Al-4V particles depend strongly on substrate properties. Higher bond strength is achieved for material combinations that show lower differences in properties (density, hardness, thermal and mechanical properties), e.g., in the case of Ti-6Al-4V on Ti and Ti-6Al-4V substrates. This is attributed to more pronounced formation of adiabatic shear instabilities for more compatible material combinations.