Grain Size Dependence of Steady State Creep Rate in Sn-1 wt% Zn Alloy

The effect of grain size as well as ageing temperature on the steady
state creep and microstructure parameters of Sn-1 wt% Zn alloy have been
studied. The steady state creep rate •εs is found to increase with ageing
temperature, whereas it decreases by increasing grain size. The relation
between •εs and the ageing temperature was fitted by a computer program and
was found to be expressed as ln •εs = Α + ΒT-1 with a strong negative
correlation coefficient ≈ –1. The values of the activation energies controlling
the creep process around the transformation temperature (423K) from (α+β)
phases to β-phase were calculated. The variations of •εs and the microstructure
parameters (a, c, Δa/ao and c/a) with the ageing temperature confirm the
precipitation process of Zn-rich phase in the temperature range (393-413 K)
and its dissolution in the temperature range (413 – 423 K).