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 Ti 3 Al contain up to ∼5.5 at.% Pt and Al 2 Pt ∼13 at.% Ti. The Ti 3 Pt, Ti 3 Pt 4 and TiPt phases extend up to 7.5, 9 and 30 at.% Al, respectively. The homogeneity range of the ternary phase τ 1 extends from Al 63.3 Ti 30.6 Pt 6.1 to Al 69.0 Ti 24.2 Pt 6.6 and that of τ 2 from Al 44.1 Ti 34.0 Pt 21.9 to Al 55.1 Ti 20.9 Pt 24.0 . The τ 3 -phase is formed in the compositional region from Al 37 Ti 37.5 Pt 25.5 to Al 42 Ti 32 Pt 26 . Only the Nb(Ir,Al) 2 -type structure of the latter was revealed. The τ 4 -phase exists between Al 31.3 Ti 33.7 Pt 35 and Al 36.6 Ti 29.4 Pt 34 while the τ 5 -phase exists between Al 12.9 Ti 58.9 Pt 28.2 and Al 27.3 Ti 57.3 Pt 15.4 . Apart from these previously reported phases, five new ternary compounds designated τ 6 to τ 10 were revealed. The τ 6 -phase exists between the Al 25.5 Ti 54.2 Pt 20.3 and the Al 30 Ti 54 Pt 16 compositions, and probably has a primitive cubic structure with a = 0.68477(6) nm. The τ 7 -phase was found to be formed around the Al 12 Ti 51 Pt 37 composition, τ 8 , τ 9 and τ 10 -phases exist in the compositional ranges of Al 28.5 Ti 55 Pt 27.5 to Al 33.7 Ti 40 Pt 26.3 , Al 34.5 Ti 48 Pt 17.5 to Al 38 Ti 44 Pt 18 and Al 32.6 Ti 44.3 Pt 23.1 to Al 37.4 Ti 41 Pt 21.6 , respectively.