ON MECHANICAL PROPERTIES OF CRYSTALS WITH COVALENT BOND

The parameter α = H/kTm characterizes the resistance of a crystal lattice to dislocation motion. For crystals with a covalent component of the interatomic bond the parameter α increases with the degree of the interatomic bond orientation. At high temperatures α determines the value of the critical shear stress and the temperature t* at which a sharp change of the temperature dependence of the critical shear stress begins. It is shown that t* = documentclass{article}pagestyle{empty}begin{document}$sqrt {alpha /} sqrt {3,c} $end{document}, where c characterizes the slope of the curve τcr = f(T) at the temperature t*. Passage of the temperature t* is accompanied by a change in the mechanism of plastic deformation. The correlation of strength and plastic properties with the degree of the interatomic bond orientation is discussed. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim