Ti-Fe alloy nanometer powders with particle size between 5 nm~30 nm were prepared by gas evaporation with arc as a heating source.The formation regularities of the phases and the melting point of the powers were investigated.The results indicate that the as-formed alloy phases in the nanometer powders are different from that in the Ti-Fe equilibrium phase diagram.FCC and TiFe2 phases were easily obtained when the master alloy rich in Fe was evaporated;by contrast,we gained FCC and TiFe phases when the master alloy rich in Ti were evaporated.The relative amount of the FCC phase is always the highest in all the powder samples.As the component of Fe in the master alloy is 53wt%,the relative amount of FeTi phase in the as-prepared powder was the highest among all the samples.A little amount of Ti phase was detected in the nanometer powders only when the Fe10Ti90 master alloy was evaporated due to the formation of the FCC phase.The lattice spacing of d(111) plane of FCC phase increased with the increase of Ti amount in the master alloys,which confirmed the solution of the Ti in the phase.The DSC curves showed that the mean melting points of these nanometer powders were lower than that of the as-formed alloy phases at equilibrium state.