Effects of heat treatment parameters on the microstructure and mechanical properties of in situ TiBw/Ti6Al4V composite with a network architecture

In situ 5 vol.% TiB whiskers reinforced Ti6Al4V (TiBw/Ti64) composites with a network architecture were heat treated with different parameters in order to further improve their mechanical properties. The microstructure results showed that the fraction of the transformed β phase in the matrix increases with increasing quenching temperatures, which leads to a significant improvement in strength at room and high temperatures. Both the size and fraction of fine α + β phases transformed from martensite phase increase with increasing aging temperatures, which decreases the strength of the composite. When the testing temperature is lower than 600 °C, the strength of the 5 vol.%TiBw/Ti64 composite is significantly enhanced by heat treatment consisting of water quenching and aging processes with proper parameters. This can be attributed to the superior heat treatment strengthening effect on the basis of the network boundary strengthening effect.