ABSTRACT
The beautiful shapes of many crystals that are found in nature represent an attempt at the minimization of surface energy per unit volume of material when at equilibrium, or because the rate of growth varies with direction. Engineering materials usually are space-filling aggregates of many crystals of varying sizes and shapes; these polycrystalline materials have properties which depend on the nature of the individual crystals. But also on aggregate properties such as the size and shape distributions of the crystals, and the orientation relationships between the individual crystals. The crystallographic direction along which single-crystal turbine blades are grown is selected in order to minimize the possibility of vibrations during the operation of gas turbines. The degree of randomness in the orientations of the crystals relative to a fixed frame is a measure of texture, which has to be controlled in the manufacture of transformer steels, uranium fuel rods, and beverage cans.
