Effect of semi-solid forging temperature on microstructure and mechanical properties of Ti14 alloy

The influence of the semi-solid forging temperature between 1000 and 1100 °C on the microstructure and mechanical properties of a new α+Ti₂Cu alloy was investigated. The results indicated that more Ti₂Cu tended to precipitate on grain boundaries at a higher forging temperature, and finally formed a network structure after forging at 1100 °C. The precipitation was found to be controlled by both peritectic and eutectoid reactions. The elevated temperatures resulted in more liquid along the prior grain boundaries, which increased the peritectic precipitation in this region and formation of precipitation zones during re-solidification. In addition, the liquid served to relax the stress concentrations caused by dislocation pile-ups within the grains and provided more nucleation sites for eutectoid Ti₂Cu precipitates on grain boundaries. Hardness and room temperature tensile properties decreased as the forging temperature increased, and intergranular fractures were observed after semi-solid forging at 1050 and 1100 °C, which is also attributed to the grain boundary network obtained by semi-solid forging.