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

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 d2 according to an empirical relation β= β
o+kd2. This was
explained on the basis of internal dislocation processes associating the
creep deformation. A critical stress, σ
c, needed for initiating the creep < br />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.