Coherent orientation relationship between an icosahedral phase and a cubic<i>α</i>phase in melt-spun Al-Si-Mn

Abstract

We report what we believe to be the first observation of definite coherent directional relationship between a cubic \ensuremath{\alpha} phase and an icosahedral phase in rapidly quenched Al-Si-Mn. Electron-microscopic studies reveal that the set of three cubic orthogonal [001]-type directions are parallel, respectively, to three icosahedral twofold axes, and all cubic [111] directions are parallel to threefold icosahedral axes, while the fivefold icosahedral directions are very close to [530]-type cubic directions. Structural models of the quasicrystal as a disordered \ensuremath{\alpha} phase are consistent with the present results.