Microindentation of dispersed phases in an Al94Mn2Be2Cu2 alloy

This paper investigated properties of dispersed phases in an Al94Mn2Be2Cu2 alloy using a microindentation hardness test. The focus was directed to the possible strengthening phases for aluminium alloys: an icosahedral quasicrystalline phase (i-phase), a hexagonal quasicrystalline approximant with a large unit cell (H-phase) and a ternary cubic Be4AlMn. A single grain μ-Al4Mn was also examined as a reference. The application of scanning electron microscopy and a focussed ion beam, significantly increased the reliability and reproducibility of the microindentation results. The i-phase was distinguished by the highest Vickers hardness and the highest fraction of elastic energy, while the elastic modulus was the highest for Be4AlMn, being close to that of pure Be. The striking resemblances of the indentation curves for the phases with cluster substructures: i-phase, H-phase and μ-Al4Mn, especially the presence of pop-ins, suggested related deformation mechanisms.