. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. FACTORS AFFECTING MAGNETIC QUALITY 281 of alloying elements, and values for the metallic and borderline elements are shown in Fig. 31. Most of the values are simply the distances of nearest approach of atoms in the element as it exists in the structure stable at room temperature. Atomic diameter is especially important in theory because the very existence of ferromagnetism is dependent in a critical way on the dis- tance between adjacent atoms. This has been discussed
. The Bell System technical journal. Telecommunication; Electric engineering; Communication; Electronics; Science; Technology. FACTORS AFFECTING MAGNETIC QUALITY 281 of alloying elements, and values for the metallic and borderline elements are shown in Fig. 31. Most of the values are simply the distances of nearest approach of atoms in the element as it exists in the structure stable at room temperature. Atomic diameter is especially important in theory because the very existence of ferromagnetism is dependent in a critical way on the dis- tance between adjacent atoms. This has been discussed more fully in a previous paper.^^ Even when no phase change occurs in a metal, important changes in struc- ture occur during fabrication and heat treatment, and these are compli- cated and imperfectly understood. When a single crystal is elongated by tension, slip occurs on a limited number of crystal planes that in general are inclined to the axis of tension. As elongation proceeds, the planes on which slip is taking place tend to turn so that they are less inclined to the axis. In this way a definite crystallographic direction approaches parallelism. (a) ROLLED (b) RECRYSTALLIZED (C) DRAWN Fig. 32—The preferred orientations of crystals in nickel sheet and wire after fabrication and after recrj-stallization. with the length of the specimen. In a similar but more complicated way, any of the usual methods of fabrication cause the many crystals of which it is composed to assume a non-random distribution of orientations, often referred to as preferred or special orientations, or textures. Some of the tex- tures reported for cold rolled and cold drawn magnetic materials are given in Table VI, taken from the compilation by Barrett.''' The orientations of the cubes which are the crystallographic units are shown in Fig. 32 (a) and (c) for cold rolled sheets and cold drawn wires of nickel. Since the magnetic properties of single crystals depend on crystallographic direction (anisotro
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