Effects of heat treatments on the microstructure and mechanical properties of as-extruded TiBw/Ti6Al4V composites

In order to further exploit the superior mechanical properties of in situ formed TiBw/Ti6Al4V composites, solution and aging heat treatments were performed on the as-extruded composites. The results show that, with increasing solution treatment temperatures, the volume fraction of primary α phase decreases, while that of the transformed β phase increases correspondingly. Both the size and volume fraction of the fine α and β phases formed from the quenched martensite phase increased with increasing aging temperatures. The hardness and tensile strength of the composites increased on increasing the solution temperature from 930 to 990 °C; however, both decreased on increasing aging temperature from 500 to 700 °C. A superior combination of tensile strength (1365 MPa) and elongation (7.9%) of the as-extruded 5 vol% TiBw/Ti64 composite has been obtained by water quenching from 990 °C and aging at 600 °C for 6 h.