ABSTRACT
This chapter focuses on the direct beam and elastically scattered beams which form different contrast images and electron diffraction patterns. In respect that the contact loading affects only a very small volume of material and, compared with all other techniques, the transmission electron microscopy (TEM) is the instrument of choice due to its unequalled capabilities of both dealing with the microstructure at high spatial resolution and providing the crystallographic information. TEM was developed initially because of the limited image resolution in light microscopy, which is imposed by the wavelength of visible light. In TEM imaging the diffraction pattern has to be obtained first, because this pattern indicates how the electron beam is scattered in the specimen. Bragg diffraction may not only provide information about the crystal structure and orientation of the grains but also create a special contrast in TEM. In TEM, the electron beam is composed of high-energy particles.
