Electron diffraction and high resolution electron microscopic study of ordering in the gold‐manganese system I. The Orthorhombic and Monoclinic I Structure in Au₁₁Mn₄

Gold‐manganese alloys of the composition Au₁₁Mn₄ are studied by means of electron diffraction and high resolution electron microscopy. It is shown how the initial stages of ordering proceed by the transformation of a DO₂₂ structure into an orthorhombic or monoclinic long periodic antiphase boundary structure. The structural models are derived from a crystallographic analysis of the antiphase boundaries as observed in the structure images and of the diffraction effects produced by the periodic occurrence of these defects. An atomic picture is proposed for the transition from DO₂₂ into the orthorhombic structure.