抄録
By means of electron diffraction and lattice imaging microscopy, new modes of order twin were found in films of the composition around Cu-50 at.%Au made epitaxially by successive deposition in vacuum, homogenized and slowly cooled from the disordered state to room temperature. Order twins (101) change the form and the size depending on the composition or the tetragonality, c/a. In Cu-40 or 60 at.%Au films, in which the tetragonality is closer to unity, the twinned layers are several tens nanometer in breadth, and the twin boundaries are distinct and parallel to the (101) twin planes which are normal to the film plane, while in Cu-50 at.%Au films, in which c/a reaches 0.927, the twinned regions are as narrow as several atomic layers, and the twin boundaries do not always coincide with the (101) twin planes but become obscure. They are often the (100) plane which is parallel to the film surface. In the last case, the misfit and overgrowth between two sheets produce a large measurable lattice stretch, which is characteristic of thin films.
