A study of the Al–Fe–Pt alloy system

Abstract

Phase equilibria in Al–Fe–Pt were studied at 850 and 1100 °C below 50 at.% Pt and at 700 °C above 75 at.% Al. The region of the (Fe) solid solution propagating up to 55 at.% Al was found to only extend up to 5 at.% Pt, the Pt solubility in the Al–Fe intermetallics is below 2.5 at.%. The Al4Pt, Al2Pt and Al3Pt2 phases were found to propagate up to at least Al80Fe4Pt16, Al45Fe25Pt30 and Al56Fe5Pt39, respectively. The formation of six ternary phases, designated Ο, Ν, C, θ, χ and ε, was revealed. The O–Al13(Fe,Pt)4 phase (Cmcm, a = 0.81357 nm, b = 1.5452 nm, c = 2.3839 nm) is formed close to the upper Pt limit of the ternary extension of M-Al13Fe4. The C-phase (Pm3,¯a = 0.76238 nm) exists between Al72Fe17Pt11 and Al74.5Fe13.5Pt12 in a temperature range of ∼1000–1130 °C. The θ-Al9(Fe,Pt)2 phase (P21/a, a = 0.8660 nm, b = 0.63780 nm, c = 0.63103 nm, β = 94.79°) is formed in a small region around ∼ Al82Fe9Pt9. The ε-phase (ε6-type, Pnma, a = 2.3297 nm, b = 1.6483 nm, c = 1.2253 nm) was revealed between Al75Fe10Pt15 and Al73.5Fe5Pt21.5. The χ-phase (P31c, a = 1.2195 nm, c = 2.7207 nm) was revealed between Al77Fe8Pt15 and Al74Fe2Pt24. The structure of the N-phase forming around ∼ Al79Fe12Pt9 was not specified.