AbstractThe microstructure, nature, distribution, and chemical composition of the different phases obtained inγ-TiAl alloys with small amounts of silicon additions have been investigated. Based on the microstructures observed and results obtained via energy dispersive X -ray microanalysis, the approximate partial liquidus projection of the ternary Ti–Al–Si system in the range of compositions over whichγalloys exist, has been established. Two four phase invariant points on which peritectic reactions occur are present. The eutectic valley betweenβand Ti5(Si, Al)3phases exhibits a maximum point, and the liquidus surface in this region is of saddle type. The results were found to be in good agreement with predictions based on thermodynamic modelling.MST/1937