Fabrication and characterization of Ti–Cu clad materials by indirect extrusion

This study was to investigate the effects of extrusion condition (extrusion temperature, extrusion ratio, dies angle, initial Ti thickness) on the fabrication of Ti–Cu clad material for high conductivity and high corrosion resistance, using indirect extrusion method in which there is no friction between container and billet. The range of extrusion temperature, extrusion ratio, dies angle and initial Ti thickness were changed from 700 to 900 °C, from 10 to 38, from 20° to 50°, and from 1.8 to 4.8 mm, respectively. Extrusion pressure decreased with increasing extrusion temperature owing to the reduction of flow stress. However, increment of extrusion temperature resulted in the drawback of lubricant effect between dies and billet. Extrusion pressure increased with increasing extrusion ratio and initial Ti thickness. Extrusion pressure was also affected by dies angle. Namely, the maximum extrusion pressure was increased with smaller dies angle because the friction between billet and dies increased with decreasing of dies angle. The thickness of interface layer between titanium and copper was increased with increasing extrusion temperature. The interface layer composed of hard inter-metallic phases which may act a reducer of bonding strength depending upon its thickness.