Effect of temperature on structure and mechanical properties of composite quasicrystalline Al94Fe3Cr3 alloy consolidated under high pressure

Abstract

Consolidation of powdered Al-based alloy with nominal composition of Al₉₄Fe₃Cr₃, which was fabricated by water-atomisation technique using high-pressure water, was performed under quasi-hydrostatic pressure (2.5 and 4 GPa) at the room temperature. The annealing of the composite quasicrystalline Al₉₄Fe₃Cr₃ alloy was carried out in the temperature range 350-600 °С. The influence of temperature on the structure and mechanical characteristics (microhardness number, HV, and yield stress, s_0.2, plasticity characteristic δ_H) of as-consolidated Al₉₄Fe₃Cr₃ alloy were characterized by XRD, SEM analysis and the test method procedures of indentation technique. It is shown that the strength characteristics of the alloy retain high values up to a temperature of 400 °C, at which quasicrystalline particles of i-phase dissolve in α-Al matrix with the simultaneous formation of the crystalline metastable Al₆Fe intermetallic. A significant decrease in the strength of the alloy occurs when the annealing temperature increases to 600 °C, which is accompanied by the conversion of the metastable intermetallic Al₆Fe phase to stable crystalline intermetallic θ-phases: Al₁₃Cr₂ and Al₁₃Fe₄.