Formation of icosahedral quasicrystals in (Ag,Au)-based ternary systems

We investigated the phase constitution of rapidly solidified (Ag,Au)-based ternary alloys at various compositions of (M,X)85.7RE14.3 (M = Ag, Au, X = Al,Ga,In, RE = Er,Lu). It is found that an icosahedral phase is formed at an average electrons per atom ratio close to 2.0 as well as at the composition ratio of (M,X)6RE, suggesting that these factors have crucial roles in the stability of the icosahedral phases. It is also found that the trend of the icosahedral phase formation in the Au-based alloys is quite different from that in the Ag-based alloys.