Creep Characteristics of Ag-4 wt% Cu Alloy at High Stresses

Abstract

Creep characteristics of α-solid solution Ag-4 wt% Cu alloy samples of different grain diameters have been investigated under high stresses ranged from 151-193 Mpa at RT. The creep results showed that the transient creep parameter n increases linearly with grain diameter d, while β varied with d 2 according to an empirical relation β= β o +kd 2. This was explained on the basis of internal dislocation processes associating the creep deformation. A critical stress, σ c , needed for initiating the creep process was observed from the dependence of β on σ. The steady state rate ε • s was found to vary with d. The stress exponent m* varied linearly with grain diameter. The obtained higher values of m* were attributed to the transition of the velocity of dislocation climb from a linear to an exponential function of stress. The dependence of ε • s on β was found to be valid with the exponent γ which has a value of 0.6.