The yield point of a super-lattice

A completely theoretical oaloulation was made of the dependence of the yield point on the degree of long-range order in an AB b.c.c. super-lattice. The resulting equation is where T is temperature, and S 0 is degree of long-range order. For β-brass a maximum in τ at 515°k of 0·54×109 dynes/cm2 is predicted; the experimentally observed values are 493°k and 0·36×109 dynes/cm2. A sharp increase in τ was observed near T c; it is associated with short-range order strengthening as predioted by Sumino. The width of an anti-phase domain boundary was also calculated. For T > 0·5T c the width is given by the equation