CREEP OF BETA-BRASS IN VICINITY OF TC

The steady state creep behavior of beta-brass single crystals was observed from 825 to 533°K. Above 650°K where the activation energy for creep was found to be independent of the stress, the creep rate could be described by the equation ε ̇ = Aσ3D/G2kT. Experimental values of D, the diffusion coeffi and G, the shear modulus were used to obtain the constant A. Although A is independent of the degree of long range and short range, it has a valve above Tc which is 8 times greater than its value below Tc. The discontinuity in A occurs at Tc. A theory is presented which quantitatively accounts for the behavior of A. The theory is based on the idea that climb and not viscous glide is rate determining for a superlattice dislocation; also the climb rate of superlattice dislocation was shown to be independent of the degree of long range order and about 12 times slower than the climb rote of an ordinary dislocation. © 1969.