Effect of Cu Content on the Semi-Solid Formability and Mechanical Properties of Ti-Cu Alloys

The formability of Ti-Cu alloys and their mechanical properties after semi-solid forging were investigated. The formability was evaluated by upsetting and die forging tests. Tensile test was also performed to study the mechanical properties of Ti-Cu alloys after semi-solid forging. The results show that the semi-solid forging requires lower upsetting forces in the temperature range from 1000 °C to 1150 °C compared with conventional solid forging. Die forging tests show that the semi-solid forged Ti-Cu alloys have an excellent workability with a forging ratio of 75% in the temperature range from 1000 °C to 1050 °C. The Ti2Cu phase increases with the increase of Cu content, and more liquid precipitates during semi-solid deformation at higher temperatures and higher Cu content, which relaxes the stress concentration caused by solid deformation and improves the formability. Tensile test reveals that semi-solid forged Ti-Cu alloys exhibit higher strength and lower ductility than conventional forged alloys. The Ti-Cu alloys have lower ductility and higher strength with the increasing of Cu content. The difference in tensile properties is attributed to the change of Ti2Cu precipitates at different Cu contents and semi-solid forging temperatures.