Abstract :
The preparation of large single crystals of silicon-iron in sheet form by the strain-anneal method is described in detail. Whole-sheet single crystals up to 2¿ in wide and 21 in long, and having a crystallographic plane either of the form {100} or {110} in the plane of the sheet, have been made successfully from 2% silicon commercial electrical sheet using Dunn´s method. Certain limitations in the orientations it was possible to produce by this means were observed with the materials used, attempts to grow crystals having a {1ll} in their plane, for example, being unsuccessful. The many factors affecting recrystallization are discussed. Carbon contents of the order of 0.015% were observed in several of the crystals prepared. One of the crystals with a silicon content of 2.11% exhibited no phase change up to a temperature of 1 140°C, i.e. 40¿50°C above the temperature at which it was grown, and examination by X-rays showed it to be of exceedingly high quality with an estimated range of misorientation of not more than ten minutes of arc. A magnetic torque curve for a 1¿-in diameter single-crystal disc having a {100} cube face in its plane is given, and the magnetization curve in the {100} direction for a ¿picture-frame¿ sample of external dimensions 1¿-in square is also included. The former shows that it is more accurate to take a figure of 89% of the unique infinite field value of the anisotropic constant K1 when analysing torque curves obtained on 0.014-in thick discs of 1¿-in diameter in applied fields of the order of 2 000 oersteds, and this figure is in good agreement with the correction suggested by Tarasov.
