ISOTHERMAL AGING BEHAVIOR OF BETA-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 measuremen ts. X-ray diffractometry and transmission electron microscopy. The Tim e-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 p hase did not precipitate by 773K aging in T-10mass%Fe, the upper tempe rature limit for precipitation of isothermal omega phase in Ti-10mass% Fe will situate between 723K and 773K. Incubation period prior to nucl eation of a phase is shortened with elevating aging temperature. The i nfluence of Fe content on the rime for nucleation of a phase was not c lear. Only at 723K, resistivity and hardness of all specimens show sec ond abrupt decrease by more than 600 ks aging, which suggests the prec ipitation of TiFe.