Impact bonding and rebounding between kinetically sprayed titanium particle and steel substrate revealed by high-resolution electron microscopy

Micrometres-sized titanium particles were deposited on a steel substrate by kinetic spraying at an impact velocity of about 760 m s-1, and the bonding between titanium and steel was characterized by high-resolution electron microscopy. A thin interfacial layer composed of titanium, oxygen and iron was identified between the particle and the substrate. Moreover, although titanium particles appeared well bonded to the substrate, their central parts did partially detach. Remarkably, the detachment occurred not at the titanium/steel interface but inside the steel substrate.