Isothermal aging behavior of β Ti-Fe alloys

The isothermal aging behavior of Ti-5,8 and 10 mass%Fe alloys at 673K, 723K and 773K was investigated by resistivity and hardness measurements. X-ray diffractometry and transmission electron microscopy. The Time-Temperature-Transformation diagram of the alloys was determined. In Ti-5 mass%Fe and Ti-8 mass%Fe, the isothermal omega phase precipitated by aging at all of the aging temperatures. Because the isothermal w phase did not precipitate by 773K aging in T-10mass%Fe, the upper temperature limit for precipitation of isothermal omega phase in Ti-10mass%Fe will situate between 723K and 773K. Incubation period prior to nucleation of a phase is shortened with elevating aging temperature. The influence of Fe content on the rime for nucleation of a phase was not clear. Only at 723K, resistivity and hardness of all specimens show second abrupt decrease by more than 600 ks aging, which suggests the precipitation of TiFe.