High-temperature creep behavior of a dispersion- and solution-hardened At-3.1at%Mg-1.3vol%Be alloy - absence of threshold stress

In order to examine D.J. Srolovitz's theory of attractive interaction between dislocations and dispersed particles, an Al-3.1 at% Mg-1.3 vol% Be alloy having effects of dispersion and solution hardening was subjected to creep tests and transmission electron microscopic observation. The creep test was conducted from 623 to 723 K at stresses from 1.8 to 51.4 MPa, which correspond to the range of 0.38-8.48σ_v (σ_v is the void hardening stress). The results show that the dislocation-particle interaction is attractive, but no clear threshold stress occurs under the conditions tested. This suggests that the absence of threshold stress may not be evidence of the climb mechanism. The reason for the absence of threshold stress is discussed from the viewpoints of solution hardening and grain boundary sliding.