The Martensitic Transformation in Ti-6Al-4V

The effect of heat treatment on the phase transformation of Ti-6Al-4V alloy was investigated. This heat treatment consisted of solution treatment at 850°C,900°C,950°Cfor 1h and subsequent water quenching. The phase transformation data was obtained by X-ray diffraction and differential scanning calorimetry (DSC).The differences were observed in the changes of lattice parameters of martensite phase among the different solution temperature. The volume of single cells for a' phase increases from 34.84 Å 3 to 35.09 Å 3 and then decreases to 34.63 Å 3 with the solution temperature increased. These changes are believed to be due to partitioning of vanadium in b phase and its strong effect on the lattice parameter of a' martensite phase. The nucleation rate function has been obtained by thermodynamic theory. Based on these equations, it could be proved that the nucleation rate of martensite should be increased with the increase of the content of vanadium and the decrease of aluminum in b phase.