Since different mechanical properties of metals result from different grain size became known, the metallurgists have been interested in finding out the true nature of the grain boundaries. Consequently, several different theories concerning the mechanism of recrystallization, grain growth, and the structure of metals were advanced and studied. These threw much light on the difference of properties between polycrystalline metals and single crystals of the same metals. The single crystals of metals were studied because they enabled the investigator to determine the important points of metallic behavior. The first work on single crystals was rather obscure and limited to isolated, though significant, observations on native metals and on large grains which were removed from severely coarsened metal parts. The aim of the present research was to investigate the possibility of preparing the single crystals from copper powder by employing the powder metallurgy technique. However, the principal differences between cast and sintered metals are the relative weakness of the adhesive forces between particles and the presence of pores between them in the case of powder compacts. The factors controlling grain growth and grain size for powder compacts depend not only upon the amount of deformation, temperature and time of annealing, but also depend upon the amount of compressing pressure and the sintering conditions of powder compacts --Introduction, page 1
