Influence of long-range order upon strain hardening

Abstract
Shear stress-shear strain curves of ordered and disordered Cu3-Au single crystals have been obtained over the temperature range 77 to 500°K. Analysis of the data indicates (i) the strain hardening rate in stage II, θII, for the disordered condition is essentially independent of temperature, and (ii) θII for the ordered state increases continuously from 77°K to a maximum at 350°K. It is proposed that the increment of strain hardening due to ordering in Cu3Au type alloys arises from a source exhaustion mechanism; dislocations from a source cannot move large distances before being held up at barriers formed by partial cross slip of superlattice dislocations. The rate of formation of these barriers is thermally activated which accounts for the increase in θII with temperature.