Structure, electrical and thermal transport properties of Sn reinforcedAl-Cu-Fe quasicrystalline matrix composite prepared by mechanical milling and subsequent annealing

The present work deals with the structure, electrical and thermal transport properties of Al-Cu-Fe quasicrystal (IQC) reinforced with soft Sn phase (10–30 vol%) processed by mechanical milling and subsequent annealing. The 40 h milled powder of IQC-Sn nanocomposite contains IQC phase along with other crystalline phases i.e. B2-Al(Cu, Fe) (a = 0.29 nm; cP2) and monoclinic Al ₁₃Fe ₄ (a = 1.549 nm, b = 0.808 nm, c = 1.248 nm; α = γ = 90°, β = 107.72°; mC102). The IQC phase was also found to be ordered from the existence (311111) superlattice reflection of IQC. The phase fraction of IQC phase increased (in comparison with the crystalline phases) on annealing of IQC-Sn powder milled powder at 800 °C. The nano quasi-crystalline and nano-crystalline nature of these IQC and crystalline phases in milled and annealed powders were observed through transmission electron microscopy. The nano-beam diffraction (NBD) of the annealed samples confirmed the presence of nearer to 5-fold symmetry corresponding to the IQC phase. The electrical and thermal transport properties of milled and annealed samples were studied. The electrical and thermal transport properties of annealed sample was higher than that of the milled IQC-Sn nanocomposite powders. The ratio of electrical and thermal conductivity for IQC-20Sn annealed sample was found to be the highest (σ/ κ ∼4704 SK/W). These findings suggest the possibility of using IQC-Sn annealed nanocomposites for potential application as thermoelectric materials.