After previous result on the solution treated at 1173K for 3.6ks and water quenched (STQ) state, the β phase was retained in alloys containing more than 4mass% Fe. Resistivity of the 515mass% Fe alloys showed the negative temperature dependence. The aging behavior of the quenched Ti-410mass% Fe β alloys with accumulative isochronal aging was investigated by changes in resistivity, hardness, and phase constitution which was identified by X-ray diffractometry. The hardness increases by precipitation of isothermal ω phase and decreases by precipitation of α phase consuming the precipitated ω phase. Above 723K, the hardness of the Ti-46mass% Fe alloys became lower than that of STQ state. In 50K/1.8ks accumulative isochronal aging, the temperature at which precipitation of isothermal ω phase confirmed by X-ray diffractometry increases with increasing Fe content. On the other hand, the influence of Fe content on the temperature ofα phase precipitation is not clear. Precipitation of TiFe can not be detected by the X-ray diffraction in accumulative isochronal aging up to 773K. The increase of resistivity of Ti-8mass% Fe and Ti-10mass% Fe alloys at room temperature observed in the aging up to 523K has been attributed to the phase separation in Fe concentration of β phase or the precursor of isothermal ω phase.
