INFLUENCE OF AL ADDITION ON RESISTIVITY A ND PHASE CONSTITUTION OF QUENCHED TI-5FE ALLOY

Previous results on beta quenched Ti-2 similar to 15%(mass%) Fe alloys suggested that the volume fraction of athermal omega phase (omega(ath )) was maximum in the Ti-5%Fe alloy. In present work, influence of Al addition to the Ti-5%Fe alloy on the formation of omega(ath) has been investigated by resistivity and hardness measurement, X-ray and electr on diffractometry in the beta quenched state. In alloys containing up to 8%Al, optical microscopy reveals single phase structure, and only b eta phase is detected by X-ray diffraction. Resistivity monotonously i ncreases with Al content. Resistivity ratio between liquid nitrogen an d room temperature, rho(LN)/rho(RT), shows a maximum at 6%Al, at which hardness shows a minimum. Room temperature electron diffraction patte rn due to athermal omega phase is changed by the Al addition from clea r spots to diffuse scattering. Similarly as the case of Ti-20V-Al, it is considered that the added Al dissolves substitutionally into beta T i-5%Fe lattice, lowers starting and finishing temperatures of athermal omega, phase formation, omega(s), and omega(f) and then decreases vol ume fraction of athermal omega phase at room temperature.