The growth of decagonal Al–Co–Ni single crystals as a function of chemical composition

Decaprismatic single crystals taken from a series of alloys of nominal compositions within Al_65–77Co_3–22Ni_3–22have been studied by means of x-ray diffraction techniques. The substitution of Co by Ni in increasing amounts changes the (pseudo)decagonal diffraction patterns drastically and indicates structural changes which range from a single-crystalline approximant via orientationally ordered nanodomain structures and quasiperiodic phases with different types of ordering phenomena, to a basic decagonal phase. A quantum phase diagram analysis shows a clear separation of the stability regions of the ternary systems described in this study and other decagonal phases.