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 e ffect 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 terna ry III-V alloys. The computed contrast behaves in the same way as the previously unexplained fine-scale contrast observer in the experimenta l micrographs of these alloys.