MODULATED STRUCTURES IN THE CU-AU AND (CUAU)-AG ALLOYS WITH ANTIPHASESTRUCTURES OF CUAU(II) TYPE

Cu-Au alloys and ternary alloys of (CuAu)-Ag containing 5-15 at% Ag, w hich have antiphase domain structures of the CuAu(II) type, have been studied by electron diffraction and high-resolution electron microscop y. Existence of the antiphase boundary steps proposed previously on th e basis of an anomaly in the splitting of superlattice reflections, ha s been confirmed in all the alloys examined on an atomic scale. In the (CuAu)-Ag alloys, a new type of modulated structure has been observed , and its nature is discussed on the basis of the diffraction patterns and high-resolution images.