ABSTRACT
C.S. Smith (1951) has cited early studies of granular structures by Archimedes (3rd Century BC), Reamur (1724) and Lord Kelvin (1887). A sketch of the granular structure of wrought iron fractured in the hot short range is reproduced in Fig. 1.1, (Grignon, 1776). Studies of regular space filling shapes were carried out by Lord Kelvin (1887 and 1894). In 1887, Henry Clifton Sorby wrote “It seems nearly certain that the separate grains are separate, though imperfectly developed, crystals”. This was based on his micro-structural studies of metals. Many practitioners believed that the structure of metals was amorphous because of the high ductility. Controversy continued for a further twenty-five years on whether metals were crystalline or amorphous, although evidence was building in favour of the crystalline state. Ewing and Rosenhain (1900), based on their studies of etch pits and slip lines, suggested that “the occurrence of such geometrical etch pits in the surfaces of metals that have never been polished may be taken as very strong evidence in support of the view that the crystalline grains of metals are built up of crystalline elements which are similarly oriented throughout the mass of each grain” - a very fair statement of the modern viewpoint. The foundations for solving the nature of metallic structures were finally laid by the X-ray diffraction discoveries of Von Laue and of Bragg in 1912.
