A high resolution study of ordering in Au4Mn. II. The evolution of ordering in Au4Mn

Ordering in the Au4Mn system is studied by electron diffraction and high resolution dark field electron microscopy. On fast quenching the alloy from above the ordering temperature diffuse streaking is observed by electron diffraction; a transition state characterized by the occurrence of tetrahedral clusters is formed. Slight annealing reveals a diffraction pattern strongly resembling the Watanabe-type structure. Dark field resolution microscopy reveals a two dimensional long period antiphase boundary structure consisting of islands of the DO22 structure; the boundaries itself having an uncommon orientation. On further ordering the Ni4Mo-type structure gradually forms while the transition structure disappears.