On the selection of Ti-Cu alloys for thixoforming processes: phase diagram and microstructural evaluation

Ti alloys are successfully applied in several sectors due to their outstanding properties. A greater increase in the industrial consumption of Ti is strongly limited by its cost, which is mainly related to difficulties in obtaining products with specific geometries. The use of thixoforming processes to form Ti alloys represents an innovative approach to minimizing such difficulties. The objectives of this study were to select and produce binary Ti-Cu alloys specifically designed for thixoforming and to investigate their microstructure when heated to the semisolid state. Specific compositions were chosen according to the criteria for thixoformability, such as the solidification range and the sensitivity of the liquid fraction to temperature. Samples of these alloys were prepared by arc melting and were then hot forged prior to partial melting. The results obtained by thermal analysis and thermodynamic simulation were in good agreement and indicated that Ti-Cu alloys can be processed by thixoforming at temperatures below 1100 A degrees C. Microstructural characterization showed fine and globular microstructures in the semisolid state, revealing the promising potential of Ti-Cu alloys as thixoformable materials.