Fabrication and mechanical properties of quasicrystal-reinforced AlMnMm alloys

Microstructures and room temperature mechanical properties of quasicrystal-reinforced Al94−xMn6Mmx (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 Al94Mn6 alloy contains hexagonal-shape particles and long needle-shape Al6Mn precipitates surrounded by α-Al matrix. An addition of Mm into the Al94Mn6 alloy generates icosahedral quasicrystalline phase (IQC) with an extinction of hexagonal and Al6Mn phases, and the fraction of IQC increases continuously with an increase in Mm content. Compressive yield strength (σcys) and ultimate compressive strength (σucs) of the AlMnMm alloys are improved with Mm content up to 4%, whereas elongation is steeply deteriorated by the Mm addition. The Al90Mn6Mm4 alloy exhibits the highest 570 and 783 MPa of σcys and σucs, respectively, both of which are comparable to those of Al90Mn6Ce4 alloy.