Fabrication and mechanical properties of quasicrystal-reinforced Al [sbnd]Mn [sbnd]Mm alloys

Abstract

Microstructures and room temperature mechanical properties of quasicrystal-reinforced Al 94− x Mn 6Mm x (Mm: misch metal, x = 0–6 at.%) alloys have been studied systematically. Cylindrical rod samples with 3 mm in diameter were synthesized by injection-casting into a Cu mould and analyzed by means of X-ray diffractometry, differential scanning calorimetry, optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectrometry. Mechanical properties of the cylindrical rods were measured at room temperature by compression tests. The Al 94Mn 6 alloy contains hexagonal-shape particles and long needle-shape Al 6Mn precipitates surrounded by α-Al matrix. An addition of Mm into the Al 94Mn 6 alloy generates icosahedral quasicrystalline phase (IQC) with an extinction of hexagonal and Al 6Mn phases, and the fraction of IQC increases continuously with an increase in Mm content. Compressive yield strength ( σ cys) and ultimate compressive strength ( σ ucs) of the Al Mn Mm alloys are improved with Mm content up to 4%, whereas elongation is steeply deteriorated by the Mm addition. The Al 90Mn 6Mm 4 alloy exhibits the highest 570 and 783 MPa of σ cys and σ ucs, respectively, both of which are comparable to those of Al 90Mn 6Ce 4 alloy.