Mechanical and Fatigue Properties of Diamond Reinforced Cu and Al Metal Matrix Composites Prepared by Cold Spray

Abstract

Diamond-reinforced composites prepared by cold spray are emerging materials simultaneously featuring outstanding thermal conductivity and wear resistance. Their mechanical and fatigue properties relevant to perspective engineering applications were investigated using miniature bending specimens. Cold sprayed specimens with two different mass concentrations of diamond 20% and 50% in two metallic matrices (Al – lighter than diamond; Cu – heavier than diamond) were compared with the respective pure metal deposits. These pure metal coatings showed rather limited ductility. The diamond addition slightly improved ductility and fracture toughness of the Cu-based composites; having a small effect also on the fatigue crack growth resistance. In case of the Al composites; the ductility as well as fatigue crack growth resistance and fracture toughness have improved significantly. The static and fatigue failure mechanisms were fractographically analyzed and related to the microstructure of the coatings; observing that particle decohesion is the primary failure mechanism for both static and fatigue fracture.