TRANSMISSION ELECTRON-MICROSCOPY CONTRAST FROM STATIC ATOMIC DISPLACEMENTS IN HOMOGENEOUS RANDOM ALLOYS

We demonstrate the existence of a new type of contrast in transmission electron microscopy. It appears in alloys displaying an atomic size effect and is induced by the field of static atomic displacements from the sites of the average lattice. The characteristics of this contrast. which exists even in homogeneous alloys, are investigated by dynamic image calculations upon very large simulated crystals of random ternary III-V alloys. The computed contrast behaves in the same way as the previously unexplained fine-scale contrast observer in the experimental micrographs of these alloys.