Microstructure and formation of melting zone in the interface of Ti/NiCr explosive cladding bar

The tube of titanium and the bar of NiCr alloy were bonded through explosive cladding technique; a good quality bonding was obtained. Melting zones are encountered in sections of the explosive cladding interface, and they serious affect the properties of the explosive cladding composite. Microstructure of melting zone in the interface of Ti/NiCr explosive cladding bar were investigated by means of optical microscope (OM), scanning electron microscope (SEM) and microhardness as well as using micro-focus X-ray diffraction and electron probe analyses. The results show that the melting zone is composed of intermetallics of brittle and stiff, and there is no element diffusion during explosive cladding process. The tendency of composition segregation of melting zone is decreased. The solidification rate and the actual distribution coefficient of solute in the melting zone of Ti/NiCr explosive cladding interface are not less than 0.1 × 108 k/s and 1 respectively. The formation of microstructure in the melting zone is result from the high solidification rate in the explosive cladding interface.

► CP-Ti/NiCr alloy bar used in medical treatment was made by explosive cladding. ► Local melting zones are encountered in sections of the cladding interface. ► Melting zone is composed of intermetallics of brittle and without element diffusion. ► High solidification rate is the major reason for the formation of the melting zone.