X-ray photographs of metals are a means of providing
information which in many cases cannot be obtained
by microscopic methods. The lines produced by each
element, or phase are characteristic, and their
general pattern enables the crystalline structure to be
identified. The scale of the pattern can be used to
determine accurately the size of the unit cell and,
therefore, the distance apart of the individual atoms.
From the relative intensity of the lines it is possible to
deduce the distribution throughout the unit cell, the
various types of atoms in an alloy or the degree of
preferred orientation in the material.