Investigation of the Al–Ti–Pt alloy system at 1100 °C

The 1100 °C isothermal section of the Al–Ti–Pt system was experimentally studied in the compositional region below 50 at.% Pt. Most of the binary Al–Ti and Al–Pt intermetallics dissolve about 1.5–3.5 at.% of the third element. Only TiAl and Ti3Al contain up to ∼5.5 at.% Pt and Al2Pt ∼13 at.% Ti. The Ti3Pt, Ti3Pt4 and TiPt phases extend up to 7.5, 9 and 30 at.% Al, respectively. The homogeneity range of the ternary phase τ1 extends from Al63.3Ti30.6Pt6.1 to Al69.0Ti24.2Pt6.6 and that of τ2 from Al44.1Ti34.0Pt21.9 to Al55.1Ti20.9Pt24.0. The τ3-phase is formed in the compositional region from Al37Ti37.5Pt25.5 to Al42Ti32Pt26. Only the Nb(Ir,Al)2-type structure of the latter was revealed. The τ4-phase exists between Al31.3Ti33.7Pt35 and Al36.6Ti29.4Pt34 while the τ5-phase exists between Al12.9Ti58.9Pt28.2 and Al27.3Ti57.3Pt15.4. Apart from these previously reported phases, five new ternary compounds designated τ6 to τ10 were revealed. The τ6-phase exists between the Al25.5Ti54.2Pt20.3 and the Al30Ti54Pt16 compositions, and probably has a primitive cubic structure with a = 0.68477(6) nm. The τ7-phase was found to be formed around the Al12Ti51Pt37 composition, τ8, τ9 and τ10-phases exist in the compositional ranges of Al28.5Ti55Pt27.5 to Al33.7Ti40Pt26.3, Al34.5Ti48Pt17.5 to Al38Ti44Pt18 and Al32.6Ti44.3Pt23.1 to Al37.4Ti41Pt21.6, respectively.

► Al–Ti–Pt alloys were investigated at 1100 °C.
► New five ternary phases were revealed.
► Partial isothermal section of the Al–Ti–Pt diagram at 1100 °C was determined.