Samples of Hot Isostatically Pressed (HIPped) powder and of forged bar stock Ti6Al4Vwhich were slowly cooled from above the beta transus and subsequently held at 500ºC for times up to 5 weeks, have been analysed using scanning and transmission electron microscopy and atom probe analysis. It has been shown that in the samples heat treated for 5 weeks at 500ºC there is a high density of alpha2 domains, which are typically 5nm in size and that a smaller density was present in the slowly cooled samples. The fatigue and tensile properties of samples heat treated for 5 weeks at 500ºC have been compared with those of samples slowly cooled from just above the transus and although no significant difference was found between the fatigue properties, the tensile strength of the heat treated samples was 5% higher than that of slowly cooled samples.The ductility of the forged samples did not decrease after heat treating at 500ºC despite the strength increase. Transmission electron microscopy has been used to assess the nature of dislocations generated during tensile and fatigue deformation and it has been found that not only is planar slip observed, but dislocation pairs are not uncommon in samples aged at 500ºC and some are seen in slowly cooled Ti6Al4V.
- titanium 64
- long range order
- tensile and fatigue properties