Stability and diffraction features of quasicrystal and 2/1 approximant phase in an Au42In42Yb16 alloy

An Au42In42Yb16 alloy has been studied by transmission electron microscopy in as-cast and melt-spun conditions. The as-cast alloy was found to contain a cubic 2/1 approximant phase (along with another crystalline phase) with lattice parameter 2.46 nm and space group P a 3 ¯ . Electron diffraction features of this phase have been described. An icosahedral quasicrystal formed on melt-spinning. Differential thermal analysis indicates that the quasicrystalline phase is stable above 525 °C, until melting. Annealing at temperature 550 °C improves the quality of the quasicrystal, while annealing at 450 °C shows transformation to a microcrystalline state. At both temperatures, a 1/1 cubic approximant phase separates out.