Abstract: The microstructure and mechanical properties of four heats of LF9 alloys bearing different Ti contents were studied by means of SEM,TEM,XRD,chemical phase analysis and tensile test.With increasing Ti content,the strength of the alloy at room temperature and high temperature increase,the plasticity and toughness decrease,the content of γ′,γ″ and η precipitates increase size of γ′,γ″ and η phase grew and morphology change.η phase play the most important role in all the precipitated phases.