Formation of quasicrystalline phases in Al-rich Al–Mn–Be alloys

Abstract The effect of Be addition on the formation of quasicrystalline phases in Al-rich Al–Mn(–Be) alloys has been investigated. A metastable icosahedral quasicrystalline phase was found to form in a 93.5Al–5Mn–1.5Be (in wt%) alloy prepared by a conventional casting technique, indicating that the addition of Be to Al–Mn alloys improves the quasicrystal forming ability. The icosahedral phase in conventionally cast Al–Mn–Be alloys forms in the undercooled melt with the equilibrium growth morphology of the pentagonal dodecahedron. Heat treatment at 540 °C for 100 h results in the precipitation of small platelets of a two-dimensional quasiperiodic phase in the α-Al matrix. These precipitates have an orientation relationship with the α-Al matrix.